It's true the west was dealing with Gadaffi before the uprisings and this is all realpolitik and there is no honor among thieves (politicians). The thing is oil would flow whether Gadaffi or the rebels were in power, the world has been encouraged to get involved with this and there's no way any evil imperialist is going to exploit Libya if they managed to rise up against such a repressive regime. I think we can conclude the motivation is political, maybe not completely altruistic but then altruism isn't a measure of morality.