The Reasoning Book explanation is indeed a rather poor one. Point #2 is irrelevant, because the exegetical choice made by Hebrew translators (who insert the name without textual authority, often on a trinitarian bias) does not constitute proper evidence. Point #5 is almost embarassing:
(5) At Revelation 22:13, the Alpha and Omega is also said to be “the first and the last,” which expression is applied to Jesus at Revelation 1:17, 18. Similarly, the expression “apostle” is applied both to Jesus Christ and to certain ones of his followers. But that does not prove that they are the same person or are of equal rank, does it? (Heb. 3:1)
The superlative epithet "the first and the last" logically entails a single person who is first (preceding all others) and who is last (postceding all others), as someone just said there cannot be two "first and lasts". It is thus not at all comparable to a title like "apostle" which can apply to any number of people who can be "sent". The discussion in the Reasoning Book completely misses the following germaine points:
(1) The title "the first and the last" is an OT epithet applied exclusively to Yahweh: "I, Yahweh, who am the first and shall be with the last" (Isaiah 41:4), "Thus says Israel's king and his redeemer, Yahweh Sabaoth: I am the first and the last; there is no other God like me" (Isaiah 44:6), "Listen to me, Jacob, Israel whom I have called: I am the first, I am also the last. My hand laid the foundations of the earth and my right hand spread out the heavens" (Isaiah 48:12). It is thus a title that explicitly addresses God's eternity and uniqueness. (2) This epithet is literally rendered in the Greek in Revelation 1:17 (cf. 2:8, 22:13) as "I am the first and the last (egó eimi ho prótos kai ho eskhatos)," and the LXX has "I am the first" (egó eimi prótos) for Isaiah 48:12, "I [am] the first" (egó prótos) for Isaiah 41:4, 44:6, and tho it renders the Hebrew word for "last" more loosely (e.g. as "into the things to come" in 41:4, "with the hereafter" in 44:6, "into eternity" in 48:12), the wording in Revelation is attested (see Field) in some Greek versions of Isaiah 48:12 (egó prótos kai egó eskhatos "I [am] the first and the last") and eskhatois "last things" is used by Theodotion in Isaiah 41:4. (3) This exclusive title is applied to Jesus in Revelation 1:17-18: "I am the first and the last, I was dead and now am living forever and ever". (4) In Revelation 22:13, the title occurs in a triplet of similar epithets: "I am the Alpha and the Omega, the First and the Last, the Beginning and the End". Each express the same thought and are semantically equivalent. (5) The equivalent title "Alpha and Omega" is applied to the "Lord God" in Revelation 1:8: "I am the Alpha and the Omega says the Lord God, who is, who was, and who is to come, the Almighty". (6) The triplet of epithets in Revelation 22:13 is also probably applied to Jesus because it is followed by the statement in v. 16: "I, Jesus, have sent my angel to make these revelations to you for the sake of the churches". The important point is not that Jesus identifies himself as speaking here, for the chapter has frequent, confusing shifts between speakers: the "angel" speaks in v. 6, John speaks in v. 8, the angel speaks for his own self in v. 9, the "angel" speaks with the voice of the Alpha and the Omega in v. 10-15, Jesus speaks in v. 16, the "Spirit and the Bride" speak in v. 17, and John again speaks in v. 18-21. Because of the shifting, the mere fact that Jesus speaks in v. 16 does not indicate that he is the speaker in v. 13. However, what is important is that he states in v. 16 that he was the one who SENT the angel to make the revelations on his behalf. The angel is thus a messenger for Jesus, and this suggests that the divine voice relayed through the angel in v. 13 is that of Jesus. Both Jesus and "the Alpha and the Omega" are also depicted as coming. (7) The two epithets of "Alpha and the Omega" and "Beginning and the End" are applied to "the One sitting on the throne" in Revelation 21:5-6, who offers "water from the well of life" to those who are "thirsty" and the one who drinks from it will have him as "his God" (v. 7). Although the place of Revelation within the Johannine corpus is questioned, it is striking that Jesus is the one who offers the "living water" in John and that his disciple Thomas confesses him as "my God" (cf. John 4:10-14, 7:37-38, 20:28). Moreover, Revelation 7:17 states that the "Lamb" is "the one at the Throne" who "will lead them to springs of living water". Regarding who is sitting at the throne, ch. 21-22 depict a joint throneship of Jesus and God with them united as the "temple" and united in shining like the sun: "There was no temple in the city since the Lord God Almighty and the Lamb were themselves the temple, and the city did not need the sun or moon for light, since it was lit by the radiant glory of God and the Lamb was a lighted torch for it.... The throne of God and of the Lamb will be in its place in the city ... they will not need lamplight or sunlight, because the Lord God will be shining on them" (21:22-23, 22:3-5). In ch. 4 and 5, the "Lamb" is distinguished from "the One sitting on the throne", yet in 3:21 Jesus says that he "sat down with my Father on his throne" and 7:17 says that "the Lamb [is] at the center of the throne". (8) The epithet "the one who was, who is, and who is to come", applied explicitly to the Lord God in 1:4, 8, 4:8, 11:17, 16:5-7, is echoed in the statement by Jesus about himself: "I was dead, and now I live forever and ever" (1:18). That the title has implications of Jesus' death and his resurrection is confirmed by 17:8 which parodies the phrase by applying it to the Beast who was killed and restored to life (a satanic parody of Jesus' own death and resurrection, see 13:3-4): "The Beast you have seen once was and now is not, he is yet to come up from the Abyss". (9) Jesus, in addition to calling himself the "first and the last" also refers to himself as "the one living" (ho zón) and "living forever and ever" (zón eis tous aiónas tón aiónón) in Revelation 1:18; this expression originally applied to Yahweh in Deuteronomy 32:40 (eis tón aióna in the LXX) and especially in Daniel 12:7 ("the one living forever" tón zónta eis tón aióna in the LXX), which is explicitly quoted in Revelation 10:6 and applied to the Creator, and the intensive form attributed to Jesus in Revelation 1:18 is applied to God in 15:7: "God the one living forever and ever (theou tou zóntos eis tous aiónas tón aiónón)". (10) Other titles applied to Jesus in Revelation originally referred to Yahweh in the OT: "the Lord of Lords and King of Kings" (17:14, 19:16) which resumes the "God of Gods and Lord of Lords" in Deuteronomy 10:17, Psalm 136:1-3 and the "King of Kings" of 2 Maccabees 13:4. (11) The description of Jesus in Revelation 1:13-16 mixes and combines motifs of the "Ancient of Days" in Daniel 7:9, 13 and angel in 10:6.
Much of this could well be inconsisteny on the part of the author (or authors, if the book is composite), but the freedom with which exclusive divine epithets are applied to Jesus indicates a very high christology involved in the book.