We don't yet know how courts will rule on cases like Does v Github (https://githubcopilotlitigation.com/case-updates.html). LLM-based systems are not even capable of practicing clean-room design (https://en.wikipedia.org/wiki/Clean_room_design). For a maintainer to accept code generated by an LLM is to put the entire community at risk, as well as to endorse a power structure that mocks consent.
We didn't have this whole issue 20 years ago because nobody gave a shit. If your code was public, and on the internet, it was free for everyone to use by definition.