Let me just be more explicit: if your software cannot be used by nazis then your software is not free software.
This is not the correct place to fight hate speech. Block the instances. Report hate speech to the authorities. Settle it using the existing legal frameworks to do so, and if they are insufficient, then write to your lawmakers.
But if you support free software, it is not the place to address this issue, by definition.
@sir what if my software license just says "you can't use this code if you're a nazi"?
@bane @ignaloidas @sir awww... but what if I say "if you use this software you should probably punch a nazi"?
@efi @ignaloidas @sir That just becomes a useless message in software but sure include it.