I would suspect that he is, if not showing concussion symptoms, maybe suffering from a lot of pain in his head. In addition to his hand, there's no point in risking your megastar at this point in the season.
I'm sort of surprised, although I shouldn't have been, to hear that he continued riding yesterday feeling a bit dizzy. When will these teams and riders learn that undergoing a concussion protocol mid race is not the end of the world? Worst case, he's cleared and can continue to ride, maybe loses GC but hey, PN is not his main objective.
Best case, he stops immediately and avoids more-serious consequences.
The other issue of him not looking good on Wednesday when Almeida motored past him is completely separate, I think.