Several years ago, there was a troll named Jeff Merkey that wrote proprietary software and had a history of involvement at Novell and Microsoft. He wrote some proprietary Linux kernel modules and lied about the license so that it would let him use GPL-only symbols, and he also suppressed the "kernel is tainted" warning so the user wouldn't see it.
From what I can tell, he's just lucky nobody decided that he was important enough to sue or get an injunction against (his business eventually went under not too long after he did that). It certainly angered a lot of kernel developers.
Merkey also had a very childish, petty, egotistical attitude and went around and tried slandering several kernel developers that made him angry, including making a libelous statement that one of them had AIDS, among other such nonsense.
It seems that particular troll is all but forgotten.
I think Nvidia would not let their employees act the way Merkey did, and I'm sure their lawyers won't let them make derivative works of the Linux kernel just because they don't want to risk the legal consequences of that.
Nvidia is pushy, and I think what they really want from Linux is something like what FreeBSD has done, where Linux developers stop caring about open source drivers or fixing driver interface bugs and just freezes "something" bugs and all, calls it an ABI, and lets Nvidia do whatever stupid things they want.