I could see it coming from about the middle of the movie, though I give them some credit for the way it was in doubt right up to the very moment of decision. To me it was an upbeat choice, though taken without a lot of joy on the part of the astronaut, more a low-key (emotionally-deadened after years of isolation) affirmation of his original impetus to explore. I don't think he had any ties to Earth holding him back anyway. After all, the mission was supposed to last a decade if successful, so I think he'd made his peace with cutting the cord.

I've thought some more about "Bob", and the choice of Bruce Baumgartner. He's a character actor with a distinctive face I've seen a lot of places, making him damn near the archetype of The Familiar Face. That's a bit of clever casting, I think, for a part consisting of being a face on a video monitor anchoring Michael's sanity. But I also agree with you that his attempt at humor about the bet was really jarring.

I'm glad you did actually enjoy the movie. I did too, and I also found things to ding it for. That's what makes this movie review stuff fun, right?