Romney made a snap judgement by stating that the assault was a terrorist attack. By jumping to the conclusion that Muslims would attack a US embassy on 9/11 just goes to show how incapable he would be as a president presiding over foreign affairs. Assuming that Muslims would plan an assault against the US on 9/11 was devoid of any rational thought.
In contrast, Obama wisely reached the immediate conclusion that the assault was due to something the US did to offend a poor nation inhabited by Muslims. He recognized that whenever there is trouble, the immediate conclusion is that the US has done something wrong once again. His was not a rash conclusion, but a conclusion derived from logic.