The general procedure for this is identify, arrest, prosecute, and imprison. Is there something I am missing? Is there some other procedure you think would be better?
They're terrorists. Do we want them in the general prison population? Do we want them to tie up the court system? Do we really want their confederates planning jail breaks?
Now how long are these terrorists going to sit in our jails, cooling their heels on our dime, while prosetylizing to the captive audience?
I suppose we could build Myanamar style camps, if they won't leave voluntarily. They are incompatible with American society by nature of their belief system. They want us dead or dhimmed. I think this is the part that you are missing. If they are not citizens, deport them if they've just been running off their mouths. If they are citizens preaching death and destruction, initiate the death penalty for treason. How does that sound?