This doesn't surprise me at all. He went on a week long cabin-in-the-middle-of-nowhere trip about a year ago to dive in to AI (that's all this guy needs to become pretty damn proficient). (edit: I'm not claiming he's a field expert in a week guys, just that he can probably learn the basics pretty fast, especially given ML tech shares many base maths with graphics)
As recent as his last Oculus Connect keynote, he extolled his frustration with having to do the sort of "managing up" of constantly having to convince others of a technical path he sees as critical. He's clearly the type that is happiest when he's deep in a technical problem rather than bureaucracy, and he likes moving fast.
On top of that, he likes sharing with the community with talks and such, and ever since going under the FB umbrella, he's had to clear everything he says in public with Facebook PR, which clearly annoyed him.
He's hungry for a new hard challenge. VR isn't really it right now since it's more hardware-bound by the need for hard-core optical research than software right now. With the Quest, he (in my opinion) solidified VR's path to mobile standalones. It's time to try his hand at another magic trick while he's on his game.
John's the very definition of a world-class, tried and true engineer/scientist. He's shown time and time again the ability to dive into a field and become an expert very quickly (he went from making video games to literally building space rockets for a good bit before inventing the modern VR field with Palmer).
If there's anyone I'd trust to both be able to dive into AGI quickly and do it the right(tm) way, it's John Carmack.