The passage in question neither proves nor disproves anything, so what is your point?
He ignores the fact that Paul never mentions someone as important as John in any of his letters to the churches and Timothy and yet by a cursory reading of John's letters to the churches you know he had not only an intimate knowledge of the spiritual condition of the churches but that the churches were intimately familiar with and respected John.
Your last comment is puzzling.
You do understand that was Jesus speaking in Rev. 2 and 3, not John. He was only the seer. The "letters" in Revelation are of a different sort than, say, the letters of Paul. "To the angel of the church of XXX write, ..." There's no indication from Revelation that John had personal, ordinary knowledge of any of these conditions. It was a supernatural revelation.
Then why would John expect the churches to believe anything he wrote if they did not know him personally and respect him? Just because he said he had a vision would not convince anybody, especially with all the itinerant preachers going around with different doctrines.