Neither does prom advocate that. He just said existing research is mostly wrong. That's not defeatist, that's realist.
That's not actually what he said.
I maintain that there's a meaningful difference between "often wrong" and "almost all" wrong and "assume all claims are bogus" and "view claims skeptically." One approach is a license to intellectual laziness (defeatist) and the other requires effort but can reap benefits.
He doesn't advocate that we give up, crawl into the fetal position, and stop trying to understand the world any more than any of the other popular statistics skeptics do.