No - we did nail Saddam, we didn't nail the problem.

If we support Libyans to the extent they want our help , and no more, they can win , then we are in a good position to negotiate with whoever ends up running the place.
It may be that the various factions will all appeal for assistance again , and we are going to have to consider who we shall support and how.

But right now, Libyan rebels are being pounded by foreign mercanaries using imported arms. And they are asking for our assistance. they don't want libya invaded, they want our air support.
Why not let them have it? Why not 'let Gaddaffi have it' in the other sense of the phrase?