Deciding on a CoC is such a low effort issue, just get it over with!
I kinda agree with the maintainers here, if it’s an issue, fork it, add your own CoC and manage your own community as you see fit. That’s valid too.
There’s nothing wrong with suggesting to adopt a CoC, but ultimately the maintainers get to decide.
They don't want to, it's got nothing to do with "effort".
Deciding on a CoC is such a low effort issue, just get it over with!