Lee has daddy issues, so that is part of his decision. Also, he was planning on leaving the service before all the events of the miniseries went down – his heart wasn’t in it any more (if it ever was; see: daddy issues, again). He just didn’t want to do it any more.
I think he made a selfish decision based on what he wanted to do, not what was best for all of humanity, and justified it to himself and to his father with the “do more good there” thing.
However. He could have done more good had he actually been an effective mouthpiece for the military’s point of view – we all know Adama can’t/won’t deal with the annoyances of the press and popular opinion and the Quorum. Lee has the touch for dealing with all of that, and if he’d actually stepped up and smoothed over his father’s high-handedness yet again, things might not have devolved to the point where Zarek felt free to make demagogic proposals to the Quorum in opposition to Adama.
But, he didn’t.
But again, what good does smoothing over the civilians’ ruffled feathers actually do? When the crap hits the fan, the entire civilian fleet is going to be lock-step with whatever Galactica’s plans are anyway, no matter how grumpy they feel about it. They need Galactica. Without Adama, they’re helpless.
If the military absolutely needs a mouthpiece, Apollo could have easily done it part time. Or just have a junior officer do it. When there tends to be 5+ space battles every year where the * future of the human race is at stake*, why devote more than 1% of the senior CAG’s time on petty squabbling? Why are there even squabblers to begin with?
If this show was at all realistic, 95% of every able-bodied person in the civilian fleet over the age of 16 would have enlisted within the first season of the show. Why there continues to be throngs of refugees doing absolutely nothing useful towards the survival of humanity is beyond me.
Prevents douchebags like Zarek and Gaeta from inciting mutiny?