@sir I have to respectfully disagree. If we don't use our power to fight for what is right, then we don't deserve that power.
My problem with your argument is that it boils down to "if nazis can't use free software, then who else will people block from using it?". I don't believe that's a valid argument, because that's not a problem that has arisen. If/when it comes up, then this discussion will be more relevant. But until that point, I don't think that "it's a slippery slope" is a important argument.
In general, I'm absolutely for free software. But in this case, when it comes to users who literally advocate for killing people, I think it's morally bankrupt to stand by and refuse to do even the slightest thing about it.
I wish we weren't in this position. I wish this wasn't a debate we have to have. I wish it were merely a case of people I disagree with on an ideological level, or people whose actions I don't approve of but are relatively inconsequential. But it's not. It's literally a matter life and death. And we have the power in our hands to do something about it.