Good point about Adama's overall dubiousness about humanity's right to survive, but I always put that down to a general sense of cynicism -- it was one of the things I really liked about him, that he didn't think people were unquestionably good or unquestionably worthy or incapable of doing wrong just because they are at war. Now I'm vaguely disappointed to find that this is coming from something he personally did, rather than just being part of his worldview.

I think he jumped at the chance to take all the blame because it's actually easier to live with the idea that you're the one bad apple than go on suspecting that your whole society is rotten to the core.

That's certainly an understandable motivation, but it really changes the character for me.