Don't worry, it's a high bar to clear. That said, Neo-Nazis easily meet it. Persistent harassment, trolling, derailment should also be dealt with as needed after warnings are given and assuming the behavior continues.
It sounds scary and restrictive but we're really only insisting on proper enforcement of Imgflip terms ("Conduct"), basically.
Thus far I haven't seen anyone but the Nazis who I think merits censorship.