The drone makes no difference except that it was the only measure taken. That is the point, they sent a drone. It's not like they did anything else later on.
Sorry can we just get this straight:
You claimed Obama responded by sending an unarmed drone. I assume you are referring to the 10:00PM drone in the timeline. But the timeline does not state that Obama send the drone because he was only notified at around 11:00PM, in fact, the timeline says that the military send in the drone.
I am not saying you are wrong, I would just like to see some evidence of your claim.