The First Amendment doesn't say "shall make no laws regard Free Speech... unless it's hateful." Hateful thoughts will still exist, and will find voice in other ways, You can't stop it by silencing it. You can only educate, and do what Gandhi suggested - be the change you want to see in the world, not force the change you want to see in the world. If you initiate aggression against hateful people, how are you better than they?