Auldsoul,
I would not dare to say that such a weak meaning as "harmony of intent" is absolutely impossible -- you might find good examples of similar phrases with a weak sense in other literature. What is certain otoh is that such a weak meaning does not suit the Gospel of John, as the network of texts quoted above clearly shows.
Side remark: it is worth noting that what Trinitarian orthodoxy has left out from the proto-Gnostic theology of John (namely, that the divine oneness ultimately applies to the elect) is precisely what the WT picks up to say: "See, it must be a weak meaning because the same expression also applies to the believers which cannot be God." Iow, they have correctly pointed out the flaw of orthodoxy but they "correct" it the wrong way (downward instead of upward), making a 50 % mistake into a 100 % one.