Reading this comment, one has to wonder what its actual relevance to the content is. Is the code of conduct somehow more important than the actual library itself?

I would say burfog thinks so. It is basically another license on the code and we have seen decades of debate on those. Never mind patent grants in license or as a separate document. CoC is another social contract and will probably be of increasing importance as cases of their use happen.

Could you explain what is cancel-culture Code of Conduct? I looked at it and didn’t find anything that would let railroading people out of the project so I’m curious what is wrong with it

It would be fine if all people were reasonable and uninterested in causing political commotion to score a win. Of course, in that case there would be no conduct issues to deal with.

So when you read it, don't think "Of course it wouldn't be used that way." (same as when a law is passed) For a person with malice, that Code of Conduct is a very effective weapon.

People will claim offense, sometimes even 3rd-party offense over things said long ago or outside the project. Others will follow the CoC maliciously or, at best, robotically. The political fight takes over the mailing lists, factions form, and actual productive contributors leave or are tossed out.