Yes, I think it's pretty clear (though yes, a lawyer can bring anything up). The basis is the propriety code case I mentioned which has been well litigated ove

Yes, I think it's pretty clear (though yes, a lawyer can bring anything up). The basis is the propriety code case I mentioned which has been well litigated over the decades, its clear definition of "derived work" (in particular for the ToS case, not calling into it) and the implication of derivation vs clean room (discussed by others in this thread). When people try to attack the GPL in court it's typically over it being a contract of adhesion, enforceability, or applicability of calling into it (none of which are an issue in this discussion). The aspects I mention above are too well trodden. (I'm talking about the USA only, of course, and I assume you, the author of the post are too).