Probadly the problem is that PC games aren't considered at art, so the general law against those forbidden signs make them illegal. And this law is in my eyes good, since i don't want the Nazi run through germany with Swastikas and SS runes. i saw one of them 2-3 month ago in the supermarket with Swastika earrings and felt very ashamed.
In books the signs are ok, when the context is ok(they can get banend when they are antisemitic) since it is art, it is also allowed for education and News. But it is generell forbidden on shirts etc., since the justice shouldn't forbid every single Item after release or a small change(and PC games are more lifestyle product for the law).