I think you're right. I wish they'd been able to toss him a line like that to lend Bellamy a little more justification (and more character development, woop).

Your second paragraph, that's one thing I love, where they had these total stereotype characters and then they break down and explain why they were that way in the first place, and then put them through the wringer and their shells burned away and their true personalities came through. Like, this is a little headcanon-y, but in my mind basically everything Bellamy did early on in the show was because of Octavia, in one way or another. He seizes power, and planned to seize power from the moment he got on the ship, because it was the best way to ensure her safety. And then all the ridiculous sleeping around and posturing and "whatever the hell we want" was partially to maintain that persona he constructed to keep power, and partially because he really did just want to let loose and be young for a change. He likely had next to no close friends/relationships/whatever on the Ark because of Octavia, and then he lost basically everything in his life because of Octavia (not her fault ofc), and so finally he's like "FUCK YES whatever the hell we want" with a handy side effect of helping him gain and keep power.

I may have thought about this a fair bit.