...in comedy, is everything. It's also pretty critical in revolutions.
The first thing a revolution does is force people to choose sides. You may hate the current oppressive leader, but if he looks likely to win, the incentive to line up with, rather than against, him is large.
By waiting until Gaddafi was on the very brink of victory, the West may have ensured that every doubter has already lined up on his side in irrevocable fashion. This could produce the worst possible result - Gaddafi triumphant, with a convincing case that much of the whole kerfluffle was a foreign plot.
The West had better figure out how to keep Gaddafi from crushing Benghazi.