He never adopted Michael, his Spock joined the very same empire he's rebelling against (and possibly died doing so.), and Surak knows what kind of shit Sybok has gotten into. And Amanda his dear, dear Amanda, God knows what happened to her in this universe. Maybe she left. Maybe the Empire killed her for being with him. Maybe she too was part of the rebellion and was killed. And then he melds with Michael and sees the life he lives in another universe, the life he could have had. Spock may have disappointed him by joining Starfleet, but he works for good. Michael instead of brutal, cruel, and ruthless, is good, kind, and willing to sacrifice herself. He's proud to call her his daughter. (Uh, yeah, Sybok, we don't talk about him...) And Amanda is alive and happy. They're happily married, they've raised a family. She looked so beautiful... He misses her. It's not logical, but he does.