That doesn't seem a) particularly useful or b) like it was hard to do before.
I could easily gather a corpus of racist slogans, a corpus of racist images, and smash them together to get a few thousand racist memes. It would probably take less time than relying on an AI model to generate each one (which takes a few seconds to a few minutes each).
And it's not as though there aren't millions of actual racists out there spewing out racist content constantly anyway.