I absolutely agree with that statement. By the same token, I watched Muslims be very much part of the solution. A number of them kept my ass safe time after time. It's complex.
An effective strategy in many aspects of life is to give people the rope that they're asking for and then watch them hang themselves with the rope. This works with kids. Take the little ones out to dinner and they sulk about eating off the kid menu. They want an adult meal. Let them have the adult meal and then force them to eat it all. Next time they'll stay with the kid's menu.
The majority of Muslims want to live in Islamic States. The longer we deny them the opportunity to do so the longer they're going to think that their alternative vision of how a society can be created is still viable. Who is around today who advocates that the USSR needs to be reconstituted because it was a better way to structure a society? Only bitter-enders. Communism has been discredited because it was given a chance and it failed. The same needs to happen with the Caliphate. They need to try it and then your friends, the dissenters, can work from within to help bring about the end. The mass of people need to realize that the Islamic way keeps them trapped in a social/religious system which is barbaric and they need to have internal reforms and revolts.
They needs to change, we can't change them. Best for us to wall them off and let them develop their own civilization without any interference from us.