The “Beloved Disciple” Isn’t John?

Professor James D. Tabor is claiming in The Jesus Dynasty Blog » The Identity of the Beloved Disciple, that the Gospel of John's beloved Disciple is none less than James the brother of Jesus.
His faulty assumption is derived in large part by his underlying denial of Johannine authorship; yet it is fueled as well by his second premise:

Anyone mentioned by name in the Gospel of John, and especially in these latter chapters, 13-21, is likely not the Beloved Disciple, on the grounds that his identity is being veiled not revealed with a name. That means we can eliminate those mentioned in John 21:1-2, as well Philip, Andrew, and Judas Iscariot.

However, I don't think we can be so certain that the appellation is an attempt to veil his identity. It reads more like an attempt to specially elaborate on the relationship shared by this disciple with Jesus.
Moreover, the disciple names himself in John 21:20,24

John 21:20,24 Peter turned and saw the disciple whom Jesus loved following them… This is the disciple who is bearing witness about these things, and who has written these things, and we know that his testimony is true.

If you accept the authorship of the gospel of John as being John, than the author has indeed identified himself.
I do accept Johannine authorship without reservation. Then again, considering the claims in the book "The Jesus Dynasty" it's relatively obvious to me that Dr. Tabor doesn't. Therein lies the problem.