American Muslims are no different than any other citizens. If you know of a crime that is going to take place, and do nothing to stop the crime by warning authorities, than you should be punished to the fullest extent of the law. Religion is no shield from rightful punishment.
I don't think that American Muslims are any worse at reporting threats than any other group in America. When they see a genuine threat, they will report it, as they should. The only time this isn't happening is when others who believe the same way keep mum to allow a person to carry out an attack. This is certainly not the norm, and not what is happening with each attack.
People have been complaining that Muslims are hiding the extremist behind the curtains of religion and while others do it out of fear. But for us to defeat the extremists, they must come out and give information regarding the same to the relevant authorities. They are aware of the radicalization as most youths go through the process in the places of worship.
If it was in general that they should do more like every one else then sure. Muslims should report a crime if they see or hear about it. But this seems question like we're singling out Muslims. Should Japanese Canadians and Americans have tried to warn the US about Peal Harbour? They probably would have if they could have but they were unfortunately to the embarrassment of both Canada and the US forced to go into camps that were like German concentrated camps. That is a whole ethnic group was probably innocent. I seriously hope we don't make that mistake again.
I say this because I don't think it's fair to place the burden of this on ONE group of people. ALL Americans should be vigilant in reporting any suspected impending acts of terrorism or terroristic activities to authorities; we are all in this together - to protect our country and its citizens.