I agree with a lot of what you're saying, but I partly disagree with the term "Karen". Yes, it is misused a LOT now (originally a term to call out racist over-complaining women) however it is still sexist. Karen is not gender neutral (it's always coded female) and racist white men are just as awful as racist white women. The TL;DR I always come back to is that we shouldn't be leveraging one 'ism against another. Or in this case we shouldn't leverage sexism against racism.
Disclaimer: I'm a strong believer in intersectional feminism, I'm mixed ethnicity, queer and have spent a number of years studying how language affects perception and beliefs (e.g. Marked Language, Male As Default, etc.).
I can explain this in way more detail and write paragraphs out on this (again, studied this for years now) if you really want more information on why we shouldn't be doing this.
I think it also helps to understand that the people asking for "free speech" and "debate" are sometimes folk that have been raised or constantly exposed to certain beliefs that inform their current beliefs and when they ask for "debate" what they're subconsciously asking for is to understand a difference in belief systems.
I am not saying certain beliefs are valid, just that beliefs are beliefs and we are all products of our upbringing and society that we live in. Some people believe awful things, not because they're awful people, but it's just that they've never encountered a different way of thinking or looking at things.
Anyway, my point is that it's not always helpful to instantly dismiss people as aholes just because they debate something. Sometimes that's people just trying to make sense of things they don't currently understand. I like to take it as an opportunity to help people see a different perspective to what they've grown up with.
The alternative is to instaban people where they'll go find a likeminded echochamber and they never have opportunity to have their beliefs challenged, never have opportunity to put themselves in someone else's shoes and learn a different way to think. That's how people become radicalised and dangerous.
(Not talking about people debating in bad faith and sealioning of course.)