Oh I agree, John couldhave used many other terms that would have been far more Grammatically correct.
But again, it's up to the translator to "make sense" of the verse, the problem is that Fred Franz failed to follow somebasic rules of translation.
One of them is that context must dictate the translation, and for the people to freak out on Jesus, it must habve meant more than a simepl " I have been".
Second, How John uses the term BEFORE Chapter 20 is what sets precedence on how it is translated in Chapter 20.
Third, when a writer makes a statement in the beginning of a book or letter then it sets the motif for the whole book or letter and when a phrase or term is used in the first instence then it aslo sets up how it is to be translated fromthem on, ex:
In the first chapter of Revelation John says how the 7 spirits are before the throne ( of God), that sets up that, whenever John says that something is before the throne of God, it is in the same "location" as those 7 spirits ( the great crowd for example).