Also, through '65, he was 'finding himself' via therapy with LSD and Peyote, the last year before LSD became a Scheduled Substance.ITTL he gets the itch for acting back, but doesn't want to devote himself fully into huge movie projects because he's taking care of his daughter. So he considers taking smaller TV roles and just happens to like a role where he gets to be the President, this time of the United Federation of Planets. He still gets to play as his persona a bit in the episodes. His fame is cemented and there's really nothing he can do that will hurt his image, so why not upstage one of America's rising TV shows with his presence?
One of the reasons for the divorce with Dyan, 2 years after the birth of Jennifer