The way to satirize fascists is to make them stupid and incompetent. It's for this reason that the Nazis in the Indiana Jones movies are probably the only proper satirical portrayal of Nazis. It's that and the Three Stooges parody of Hitler and Mussolini. As we can see irl with Zionists, fascists revel in depravity. They do not give two shits that they are portrayed as inhuman because they fucking relish that shit with a shit-eating grin. But stupidity and incompetence? They hate being truthfully portrayed as the buffoons they are. Of course, space marines will never be portrayed as stupid and incompetent because who's going to blow their money buying overly priced figures of the stupid and incompetent faction?

Fascists believe in embracing contradictions, lies, and hypocrisy. They don't really believe in anything beyond base carnal urges. So it's basically impossible to criticize or mock them because they can just edit the version of reality in their brain to make them feel cool again. This is why you just need to bash them out of existence, there's no "owning" them, they just have to stop being.