Islamists claim they speak for all Muslims. If certain Muslims do not want to be represented by the Islamists, they must act accordingly. If they do not, the logical default assumption is that they are at least passive accomplices.
In the 30s and 40s the Nazis proclaimed themselves as the representatives of all Germans. Quite a few Germans fled the country and worked or fought to defeat Nazism. They were generally accepted as fellow fighters by the Allies. Those who did not were treated by default as supporting the Nazis. We did not assume that anyone not wearing a Nazi party pin was a "good German," which is the PC position today with regard to Muslims. Sheer idiocy.
Absolutely! Those that disagree with islamic terrorists must act accordingly.