I don’t think they can be force applied to everyone who contributes

This is certainly an opinion, but here is a list of major projects that have a code of conduct: opensourceconduct.com/projects . How well those projects enforce their CoCs, idk. But they are applied, otherwise they wouldn’t bother writing out a CoC.

it’s not fair to hold people to standards they didn’t personally agree to

Software development is not the only place which holds people to standards. The realm of criminal and civil law, education, and business all hold people to standards, whether those people like it or not. In fact, it’s hard to think of any realm that allows opt-out for standards, barring the incel-ridden corners of the web.

this guy might have just decided to make a project

Starting any project – as in, inviting other people to join in – is distinct from just publishing a public Git repo. I too can just post my random pet projects to Codeberg, but that does not mean I will necessarily accept PRs or bug reports, let alone even responding to those. But to actually announce something, that where the project begins. And to do so recklessly does reflect poorly upon the maintainer.