> I am counting on the fact that _companies_ would be too worried about legal uncertainty to try this

Oh, my sweet summery child :-)

Companies have been doing far more dodgy things, things that look objectively illegal where-as the clean-room reverse engineering thing looks to me (caveat: not a legal expert at all) to be legally defensible, for a long time, definitely pre-AI.

Even if a company operating in your jurisdiction, where you as an individual might have a cat in hell's chance of even trying to sort the situation to your preference, might not, you can bet your last <currency unit> that a company elsewhere will feel more free to do so if they wanted what you have without agreeing to your terms.