I don't really see the LLM use as anti-GNU. It would be no different if the code was written in a proprietary IDE with fancy code completion. GNU doesn't restrict contributors to using exclusively free software for their contributions (if they did, they likely wouldn't have gotten very far considering how much work apple did on GCC). As long as the license is free and GPL compatible, it isn't inherently non-GNU (though, they'd encourage you not to use a SaSS for your own sake)

Now, is LLM code in the hurd a good thing? No, absolutely not. Ignoring the licensing limbo of LLM output that still isn't settled , LLMs make pretty bad code often enough that I wouldn't trust it to work on something as niche and relatively undocumented as the hurd.