I think that at least the last three of his points are, in some form, even part of much of the "historical Jesus" idea.
The Angelic/Celestial Jesus Thesis: It's pretty clear that this is but a tiny step from Paul's "life-giving spirit".
The Fictional/Literary Jesus Thesis: Born from gMark, which has enough pointers in it that make it sound as if the author doesn't want to be taken literally. Markan Priority takes care of the rest.
The Composite Figure Thesis: I think this one comes from the fact that several different figures in Josephus' books pretty much encounter specific gospel pericopes.
All three points don't clash with a historical figure being at the basis of the movement. If much of the NT story was developed by a group that didn't know much or nearly nothing of a historical Jesus (see Paul as example), you get the two-step process of mythologizing and subsequent historizing, and the resulting second "historical" Jesus won't have much in common with the first one.
I think this point is clear to most posters here, but I wanted to stress that the differences between the "mythicist" positions and those of many historicists is miniscule.