Scaling AI use in highly-collaborative environments, which open source projects are, is very challenging. I totally understand the apprehensiveness around it.
How is it challenging for open source projects? You just write a PR, and try to get it to meet the maintainer's quality bar. That's exactly how all code is written in any environment - you do code review and refine a PR until its good enough to be merged
With AI and how a lot of people use it, the quantity of written PRs goes up, but the quality goes down, and the maintainers of the project, who are often volunteers, now have to deal with this in addition to the standard work they've been doing before.
Eg if you check out Godot, initially they were cool with LLM code, and then had to clamp down on it because it was not leading to anything good