Condolences to the family of Mr. Vile Rat, it's sad to see anyone die too early for no good reason.
It would be ironic but not impossible if the people that rebelled against Gaddafi are the ones responsible for the embassy attack because this happened in Benghazi, the city that hosted the rebellion which spread from there. If so, its a case of blowback, unintended consequences.
Besides, if you help a more radical people to get into power by removing stabilizing elements of a region, don't expect them to become gentlemanly and kind even if you've supported and put or allowed them to get into power.
Just like how Saddam was a US ally, used against Iran and then went on committing atrocities, or the mujahedeen (sp?) trained to fight the Russians that have been fighting NATO and the US in Afghanistan. Libya itself is in a civil war since NATO's humanitarian intervention, the stabilizing element (Not necessarily a good government but kept everyone in check) in that region has been removed causing a power vacuum and chaos between the many large tribes that call(ed) Libya their home.
I don't expect anything to improve by use of force in such a manner. It only leads to perpetual, useless wars, having to constantly invade the same countries over and over again until no one's left to rebel or until you're thoroughly bankrupt and weakened from the expenses and losses of constant war that you can't defend yourself, let alone people thousands of miles away.