1) Killing people is wrong, no matter how horrible they are.
2) People who say and do horrible things cannot simply assume that law and convention protect them; by stepping outside the boundaries of a tacit social contract, one forfeits the prerogative of appealing to that contract.
3) ‘Free speech for me, but not for thee’ is not free speech in a free society; advocates for freedom to say what one party wants, but penalties for saying what another party wants, are simply not talking about ‘free speech’ in the relevant sense. If they pretend that they are defending free speech, they may be cynical or self-deluded, but serious discourse should pay no attention to them.
4) But not kill them.
5) In general, public discourse should attend a great deal more to evidence and warrants and qualifications than on speculation and defamation and groundless shouting.
6) But still not kill people.
7) Inciting violence — affirming in public discourse that violence, deadly force, is justified when directed against certain others runs the predictable risk of provoking retribution under colour of self-protection. Those who incite violence forfeit the protection due to peacemakers.
8) But that still doesn’t make it right to kill people.