> Integrating AI-assisted PRs into an existing team is a skillset all in itself.

What exactly is this skillset? Why should AI created PR's be any different from other PRs?

To me this seems like a very sensible move.. they don't want to deal with bad code from uninvested contributors. I can't possibly see how that would harm them. If they want to use AI themselves, given their track record I trust they would do it tastefully.

Quite simply, volume. Detailed human review is a serious bottleneck on code merging. Skillset includes how to make sure you can get quality code at speed without 100% in-depth human review. I wouldn't recommend merges without human eyes, but there is a spectrum of depth in review.