Yeah, "ultimatum" is a somewhat strong word. I do want to be clear that I don't mean that it was in any way an ridiculous request/demand/ultimatum: expelling them from the community would in my opinion have been the right thing to do, and in my opinion is an entirely fair thing to insist on and not be willing to compromise on.

What I mean to convey is that, if someone makes a demand that they're unwilling to compromise on or discuss, and you're are unable to satisfy the demand as stated, regardless of whether you want to seek a resolution along those lines, you have no good options. Of course in a healthy project there wouldn't be much need to discuss banning people who are harassing other community members. But mechanically it still has the downside of an ultimatum, even if the connotation of the term is wrong.

That is why I chose that word, and I apologize for not having been clearer about what I meant with it.

I do agree that greater willingness to use implicit political authority is generally a good thing for healthy projects. (Though maybe there is something complicated like not actually having technical control of the relevant IRC channels or something annoying like that, I don't know. In some open-source projects I'm active in, the core teams' ability to respond to harassment is somewhat weakened or at least rate-limited by using IRC servers, code-review forums, etc. run by unrelated teams, and I've seen people be hurt by abusers taking advantage of this technical limitation.)