Nope, it has literally zero credibility. When they've tried to be specific, one GOP pol said that it was the fact that the bank's board was now staffed primarily by women and POC's, then hastily added, "I don't mean to imply that white men could have done any better, but the whole diversity requirement must have been such a distraction that they just screwed up."
So you see, the only way to make the argument is to either say something overtly racist/sexist, or else make a silly non-argument about "distractions."
Pro-tip: If anyone wants to try to back this argument up, please be specific as to how and why, preferrably something other than "white men are better at running banks than women or POC's are" and try something a little more sound than "they were so distracted by these diversity requirements that they didn't even notice they were making bad investments." Because LOL, if you want to come across as developmentally disabled without actually being developmentally disabled, that's how you do it.