The term "social network" applies in meatspace. They're not just trolling Facebook.
How are those quotes supposed to be making the point you think you're making? The regional FBI director is saying that 1/4 of their investigations started as a result of tips from the Muslim community. Those quotes don't reject that statement at all.
shah and I posted a whole list of examples of where the Muslim community is actively working with law enforcement. Shit isn't just made up, yo.
First deterrent is their religious community, its tribal culture and its inevitable scorn.
Second deterrent is Patriot Act, by which even minor infraction will result in 10-20 years in jail, in best case and disappearance without access to due process in worst case.
So to sum it up: Religious Muslim has a good degree of sympathy to all those Al Qaeda ISIS freedom fighters and large disenstive of being community pariah if informs.
Secular middle easterner has no incentive to inform out of fear of being dragged into FBI corrupt web of lies and entrapments.
American Muslims don't want their community to be the one where a suicide bomber or mass shooter came from. The few examples we have are lone wolves. They weren't things the community would have known about. This isn't Molenbeek, where a significant chunk of the population is aiding and abetting a cell of terrorists.