It's a response to a very difficult problem. But it's unlikely to do what he hopes as the radicalisation seems to occur online.
Also, it punishes the (possible) 85% of Moslems who have no time for ISIS, which is harsh.
On the other hand, the possible 15% sympathy group is a whole new problem for a county to face, amongst whom a small number of actual terrorists swim.
I dunno what to suggest other than to support Reform Islam. A long project to put some secular edges around a faith that isn't merging in Europe and is unlikely to do anything different in the US if its percentage of the population expands. And to prevent Saudi money from spreading Wahhabism, which is toxic. I'd have no problem with banning Wahhabis.