Because pretty much everything he's advocating for is the exact opposite of fascism, and because we saw his Reddit comment history which he wasn't expecting to have exposed and there's no fascism in it and there is some anti-fascism. Some bad-faith mischaracterizations aside, there is literally no reason at all to think he's a fascist in any way, and a few different reasons to think he is the opposite of that.
Anyway, what makes you say that he worked in Abu Ghraib? Or is it no particular reason, just "it is known"?