If a software is truly wide open source in the sense of “do whatever the fuck you want with this code, we don’t care”, then it has nothing to fear from AI.
Open source is about sharing the source code. You generally need to force companies to share their source code derived from your project, or else companies will simply take it, modify it, and never release their changes,and charge for it too.
Sharing is caring, being forced to share does not foster care.
Companies don't care, so if you release something as open source that's relevant to them, "companies will simply take it, modify it, and never release their changes,and charge for it too" - but that is what companies do, that is their very nature, and you knew that when you first opened the source.
You also knew that when you picked a license, and it's a major reason for the particular choice you made. Want to force companies to share? Pick GPL.
If you decide to yoke a dragon, and it instead snatches your shiny lure and flies away to its cave, you don't get to complain that the dragon isn't playing nice and doesn't want to become your beast of burden. If you picked MIT as your license, that's on you.
Can't release someone else's proprietary source under a "do whatever the fuck you want" license and actually do whatever the fuck you want, without getting sued.
Only more reason for OSS to embrace AI generation - once it leaks into enough widely used or critical (think cURL) dependencies and exceeds certain critical mass, any judgement on the IP aspects other than "public domain" (in the broader sense) will become infeasible, as enforcing a different judgement would be like doing open heart surgery on the global economy.