Yahtzee almost always brings diversity up in the context of videogames and their design. I think one of the problems people might have with him is that his ideas assume a level playing field which is not what we're playing on. As one of the posters you quoted mentions, he often seems to follow the "truth is in the middle" fallacy which while quite flawed is at the very least well-meaning and permissive to dissenting viewpoints.
The problem with trying to argue for creative voice being heard above all things is that in our current climate not all voices are heard equally. The argument for vision being paramount works in an ideal world where there is currently no issue with equality, while as it stands we're in a climate where marginalized voices are struggling very hard to be heard. When we do have these less-represented groups currently engaged in that struggle and as part of our videogame demographic, views on diversity like the one Yahtzee proposes without ever being hateful do slow down movements towards correcting the issue. It's not a good argument because if we really were interested in creative vision above all else we should absolutely be working towards fixing the problem for the sake of making sure that meritorious ideas are heard and come to fruition regardless of the sex, color, etc. of the person with the idea.
His "hero and damsel" thing is ridiculously flawed as well, but it's quite self-evident so I won't go into it.
Basically I can see why someone would have issues with what he's saying and there are quite a few things I disagree with him on. I don't think, however, that these constitute bigoted thoughts. Yahtzee has lots of time to prove me wrong but in the meantime I don't see a reason to pull out the torches and pitchforks on him.
