The site doesn't promote hate speech, it allows free speech. Also I think you're overstating things.

The question of how to address this issue while maintaining free speech is a more complex one.

Free speech and censorship are mutually exclusive. Reddit already has mechanisms to allow community censorship (report posts, post deletion by moderators, banning, invite-only subreddits, etc.), but paid reddit employees only step in when things get out of hand.

Also the community is very fickle. Any perceived censorship by reddit employees that seems suspect and they get out the pitchforks. This has happened a few times (e.g. the Sears incident).

I do think the front page could be better filtered, though. Right now the default reddit front page is pretty... weird.