You're right, waiting over a year for ineffective UN intervention to never take place was far too little time; hell, 12 years if you want to go back to GW1.
So, that point "isn't even debatable anymore" according to who, you?
I think its hard to argue that the US isn't considered a world leader, whether you gauge that through power, influcence, economics, or what have you. Leadership means that you don't often do things to get others to like you, you do them because their the right thing to do, regardless of whether its popular.