Islamic terrorists are islamic by definition, just as Irish terrorists are Irish by definition and white supremacists who commit terrorism in the name of white supremacy are white by definition, but it's just not cool to speak against the entire group. My own brother is an ignorant racist, but I'd be offended if people assumed I shared his views just because I share his DNA, let alone his general ethnocultural description. If you want to isolate and de-legitimize the extremists, hate-preachers, and terrorists, forging common bonds with the greater community they come from is the best strategy available, not to mention giving you access to the best possible intelligence.