There's a big difference between a well considered high quality contribution made using AI as a tool and "claude find and fix an issue in this repo so I can put on my resume that I contributed to a high profile project". The problem is that it takes considerable time of the reviewers to filter out the high quality contributions vs the low quality ones.

I do think closing off contributions is a big step and would rather most projects find a middle ground, but it's definitely understandable why they did this.

How would they know for sure if the submitted code was written by a human or AI? If they had a “no-AI” policy, there would be no way to enforce it.

The policy makes sense to me given the security concerns for the project.