That being said, my sense is that Zenimax is having a bit of regret for not investing early and are trying alternative methods to get "their share".
From a common sense perspective, ZeniMax AFAIK wasn't even working on VR at this time period other than Carmack dabbling in his own "free time", so this is a pretty naked attempt for them to make the claim that anything he worked on even remotely related to games is owned by them, which I have a huge issue with (even if it is a concept that holds legal water in some states).
I'd have more sympathy for ZeniMax if they were bullish on VR and Carmack was working on an official project for them in the VR space and then left for another company, but this doesn't look like that at all, this looks like a game company owned by a lawyer trying to get a big payday on an opportunity they previously missed the boat on, using tenuous legal technicalities.
By this reasoning, the patent office employing Albert Einstein owned the theory of Special Relativity and presumably therefore a stake in subsequent commercialised technological development?
It makes me feel physically sick that this is a thing.
I had a probably similar clause in an old contract, anything I built or indeed thought, in or out of work belonged to the company.
Only if they have been explicitly protected. Copyright is the only protection that's automatically granted; patents need to be filed explicitly. If Carmack's claims are correct that none of his work has been patented, and that Oculus didn't use any code that he wrote while in the employ of Id, then he's in the clear and ZeniMax doesn't have a leg to stand on.