I do not think there’s much risk to hosting a forum talking about piracy, even less so when your forum is simply connected to it.
Im personally not a big fan of defederation. It just seems to split the user base, it’s extreme like cutting your arm off to avoid some poison ivy. In the end, it reduces the amount of users a post gets too and reduces the number of comments and general engagement. It has its place and I don’t think this was it.
It’s also annoying to have to create different accounts. I didn’t quit Reddit to start using 5 different mini reddits one at a time.