Debate is a fine thing with people close to your interests and mindset looking for shared consensus or some such. Not for enemies. Not for someone spamming your open source project with LLM nonsense who is harming your project, wasting your time, and doesn't deserve to be engaged with as an equal, a peer, a friend, or reasonable.
I mean think about what you're saying: This person that has wasted your time already should now be entitled to more of your time and to a debate? This is ridiculous.
> I really wonder if this has literally ever worked.
I'm saying it shows them they will get no engagement with you, no attention, nothing they are doing will be taken seriously, so at best they will see that their efforts are futile. But in any case it costs the maintainer less effort. Not engaging with trolls or idiots is the more optimal choice than engaging or debating which also "never works" but more-so because it gives them attention and validation while ignoring them does not.
> What is it about legitimacy that's so scary?
I don't know what this question means, but wasting your time, and giving them engagement will create more comments you will then have to respond to. What is it about LLM spammers that you respect so much? Is that what you do?. I don't know about "scary" but they certainly do not deserve it. Do you disagree?