Earlier quoted context omitted.
Excellent idea! Just rename it political-libc for all the people who want politics mixed in with their C library.
The FSF and its GNU project are a political endeavor. For a less-political (non-political doesn't exist) libc one might fork into linux-libc or similar. (I'm not saying that's appropriate thing to do, as I'm just a lurker enjoying the free work by others in glibc's regard, but wanted to make the point)
But neither has anything about abortion policy in it's public declaration of goals.
So, while some political messages might make sense in GNU technical docs, I don't see why a warning making an oblique reference to the Mexico City policy is not only acceptable but so critical that central leadership needs to overrule the specific project's maintainers to preserve it.