It's the good old copyright Mexican standoff. If it is ruled that decompilations are illegal, that shoots freedom in the foot, and even legal clean-room decomps can be taken out, but also ai models could be much more copyright restricted. It's both a win and a loss for everyone, as tightening the copyright noose is exactly what companies want, so they have a lot more ammo to shoot at foss projects and competition with.

The other way is that this is considered fair use, as the ai is not verbatim recreating code, it's recreating its own interpretation of the code, which is a flying spaghetti monster that only looks somewhat like the real thing only if you don't open the hood. This, of course, opens the door to being able to use ai models to break down things legally, a win for decompilation, a win for security researchers, but also a big L as well, as now obscuring code behind closed source is not good enough.

In either case, hackers and do-bads will run their own models and decompile things faster to find flaws and break stuff. Making it illegal doesn't stop determined badders from doing it. Pandora's box is already open, there is no undoing this without society as a whole getting washed away.