Proprietary source code would not usually end up training LLMs. Unless its leaked, how would an LLM have access to it?
> it would require speculative copyright owners to disassemble their binaries
I wonder whether AI might be a useful tool for making that easier.
If you have evidence then you can get courts to order disclosure or examination of code.
> And plenty of proprietary software has public domain code in it already.
I am pretty sure there is a significant amount of proprietary code that has FOSS code in it, against license terms (especially GPL and similar).
A lot of proprietary code is now been written using AIs trained on FOSS code, and companies are open about this. It might open an interesting can of worms.