If it's a pretty common characterization then why do we need yet another version of it?
Because people still aren't aware of this common scholarly interpretation, as you've demonstrated yourself. It's interesting stuff and I'm sure he has a lot of subtle nuances to his argument that are different from the stuff I've read in the past that makes largely similar arguments (as far as I can tell from what I've read about this book).
So scholars can't be wrong, biased, opinionated? I beg to differ.
Of course his degree isn't relevant, but he boasted about having "20 years" as a historian.
Of course they can, in which case you actually read their argument and pick it apart when the bias or incorrect information leads it astray. Academics do that
all the time to each other, and people outside academia are welcome to do so as well (they just often haven't read all the minute sources and dozens of related books to be able to spot the minor problems that are inevitable in any work). But what you
can't do (of course literally you can, I'm really arguing you shouldn't do) is dismiss the argument because of the author's religion, race, gender, or other superficial characteristics. If those have led to bias, then go into the argument and point out where the argument isn't actually well supported by the evidence and show what other evidence points to a better alternative. Don't go "oh but he's a Muslim he can't write about Jesus"