I side with Carmack on this one. He was one of a few owners of id, and could do whatever he wanted within the company, but didn't have the resources to research some things like VR, so when ZeniMax made its offer, it was the opportunity Carmack thought he needed to fund his research. When it turned out ZeniMax wasn't interested in Carmack's research and had its own agenda with its new employee, Carmack packed up and left to follow his heart. Now bitter at losing their investment in human capital, ZeniMax is trying a money grab.
That's my take on it from what information is publicly available. The most important thing now is what the lawyers can finagle.
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