Supposing I'm Fred The Fed and I want to shut down Hexbear.net
What if I try to make a case that admins tolerate sharing copyrighted material in violation of Statute XYZ, so the site is illegal and should be seized.
You might say, "Copyright laws are dumb, man! Who cares!" but that doesn't matter. Tell that to the law.
Should we get a lawyer's advice on this? What steps does the site need to take to avoid heat?
It's not worth thinking about. If the feds or anyone else wants to shut Hexbear down, they will find an excuse. Or they won't and they'll do it anyway. The feds don't need a reason to shut down something like Hexbear and no amount of hand wringing will stop it.
And I'm telling you that would be meaningless. You don't have to break the law for the feds to shut you down. Even if you're legally in the right you'd still have to go to court over it, you'd still have legal fees, and you'd still lose even assuming you could afford it. "The Law" only applies to folks who can afford the law and even then only if the government decides to let it.