The article does suggest that because other mediums and other games suffer from "whitewashing" (by using white people for coloured roles), we should start "racebending" by putting people of colour into white roles. That doesn't make any sense at all; it's just including different races just for the diversity of it, and all it does is further the tokenism of "look, there's a coloured character! we're not racist at all!"

I'm also not particularly fond of this argument:

Further, the defense of excluding people of color from a fantasy game is nonsensical. We are talking about being comfortable with the inclusion of wraiths and magic, but not the mere existence of people of color. Accuracy and realism flew out the window with the harpies.

There's a difference between realism and realistic; a game depicting a setting heavily influenced by slavic mythology is quite obviously going to draw from, well, slavic mythology - which again draws from the slavic culture. Allowing magic and monsters into the setting is not the same as throwing all sense of realism out of the window. The point of a fictional setting like this is that it's based on medieval (in this case, eastern european) culture, with the addition of a lot of mythological elements. That doesn't mean it's necessarily appropriate to change other realistic aspects of the setting into unrealistic ones just because you want diversity. He flat-out says that it's wrong for people to accept fantastical creatures in games but not accept people of colour; to me that's two entirely different things and not at all appropriate to compare.

The sentiment of wanting more diversity in games is a perfectly good one; but to me the author of the article doesn't seem to want just more diversity in games, he wants more diversity in specific games that don't really have any space for it. To me it's all about context and appropriateness; putting these elements into video games just because, and not making it fit through any sort of argument beyond "why not, it's all fiction anyway?" is wrong.