Authorship of John, Part 9: Could the son of Zebedee have witnessed the Passion?

Here I discuss a second much-used line of argument that the author of the 4th Gospel can't be John the son of Zebedee--namely, that Mark (and the other Synoptics) don't mention his presence at the cross. Richard Bauckham admits that this argument is used to claim that the entire idea that the Beloved Disciple was present at the cross is fictional. He rightly rejects that conclusion but tries to wield this same argument for his own conclusion that the Beloved Disciple was not the son of Zebedee and that this explains why Mark doesn't mention his presence following Jesus from Gethsemane or at the cross. I argue that this entire line of argument is wrong and that, if it worked, it would work just as "well" against Bauckham's own position.