He was also slamming the Monoprice subs
in favor of his own products too (and, fwiw, its a pretty sure bet that the Monolith 15" would wreck the PSA 18"). But I think you are ignoring the subtext of his comments: panic. He knows the designer of these subs, so he knows that they are the real deal. Don't pay attention to his bogus analysis.
As for his fairness to Monoprice subs, I can only speak to the 10" and 12" at the moment, since those are the only ones I have used so far. Without giving too much away from an unpublished review, the Monoprice THX subs are really good. With respect to their competition, they have some real advantages. This review should be published within May, so you can see what their advantages are exactly by the end of the month, hopefully.