He's honourable, but I found that part and also the idea that he'd been okay with handing over kids in 1965 quite telling for (and appropriate to) the character - because he's also, when it comes down to it, obedient. It's not a coincidence I think that he's "Captain" Jack, always part of a military or paramilitary.
The Doctor, in those circumstances, would have said "no, fuck you all, I'm going to turn the entire fabric of spacetime upside-down so I don't have to do anything bad". He wouldn't have sacrificed anybody consciously. (The tragedy of the Doctor is that whatever he does, people end up dying, even if he tries his best to avoid it, not that he ends up in situations where he is forced to do bad things.)
Jack, though - despite being immortal and having little personal risk resulting from his decisions - takes people's word for things and obeys orders. Sometimes he refuses orders, and after the fact, yes, he feels guilty about it and fucks off out of the solar system to avoid dealing with it. But in the end, despite the Square Jawed Hero image, he always seems to be "unavoidably pushed" into doing things that he then regrets.
This is my current theory anyway and I reckon it's Saturday-night-defensible.