Neal,
I think this thread has taken sort of an odd left turn into issues of semantics. Obviously, Thess himself doesn't consider White, Svendsen, etc., to be "experts of Catholicism" -- which is why he put that term in quotes. Rather, he's pointing out that they appear to be viewed as "experts" on Catholicism by some non-Catholics.
An example might be Gromit's recent thread, where (referring to those gentlemen's works, among others) he says, "I would encourage all Baptists and Protestants to read the following works. I mean you *really, really* need to read these. Here they are~"
Honestly, I don't think Gromit meant "read them to see how full of errors they are" or anything of that sort, but rather that they should be read because he trusts the "expertise" of the authors in the matters about which they wrote.
Anyhow, I don't see how you've interpreted any of this as Thess's personal "criteria for being an expert" -- that seems to me to be a good ways off base from what he was talking about. (I suppose they might possibly be Gromit's personal criteria, since he appears to trust in their "expertise," but you'd have to ask him about that).
God bless,
Mark