It's fairly common for the troll to then start a meta-argument about the code of conduct, or, to accuse others of violating the code of conduct. Eventually the notion of "don't be an asshole" tends to win the argument, but it can take a while.

If you need a code of conduct to keep someone like him away, your project was dysfunctional to begin with.

What makes you say that?

Communities have existed since the dawn of man and CoCs weren't necessary to keep idiots away. When someone is an idiot, you don't need a set of rules to identify that he's an idiot, and to have a basis to kick him out. If you 1) can't identify idiots or 2) can't kick out idiots, then you have a dysfunctional community or no teeth. CoCs can't fix a community or make you grow teeth.

Communities have had published standards of conduct since the bronze age.

> you don't need a set of rules to identify that he's an idiot, and to have a basis to kick him out

afaik, a code doesn't exist because of an inability to identify or to (attempt to) exclude a person.

i think "to keep someone like him away" is a bit of a red herring.