Dont forget lot of their supporters are young and vulnerable people also those with strong hatred for west for the things that has been done to them in the middle east. We in the UK weren't a target until we started doing what USA wanted and followed them blindly regardless whether it was right or wrong for us.
The people with hatered dont care for reasoning or what is right or wrong be it muslims or non-Muslims, they will try and justify using any reasons they can think of for their actions and thats why you will find muslims dont support those people or those puppet regimes.
Couldn't the same be argued by others for the muslim invasions and associated rapes, massacres and slavery throughout history, including relatively recent events such as Smyrna?
Doesn't the example of mohamed's life give justification to the aggressive interpretation?