Honestly, I thought the dirty talk wasn't a problem. I've had chats with my partner that were just as weird. Neither of us want to actually commit violence against each other.
I think the documentary I saw about Armie keeping a woman tied up and overstepping her boundaries in a BDSM scene so she felt really frightened for her safety - that is a lot more concerning to me than cannibalism fantasies. Who cares what the sexual fantasies are? Fantasies don't hurt anybody. My own fantasies are in a word, fucked up. But I would never act on them.
The thing that I think deserves more attention is the actual alleged abusive behaviour. If he actually abused people, THAT is what he should be cancelled for. As a vegan, it also disturbs me to hear him say "I've cut the heart out of a living animal and eaten it while it was still warm". That's animal cruelty. I hope he didn't actually do that.