Enemies of the state who plot acts of terror should be executed, not released to train other jihadists to complete their works.
It doesn't sound like they had a case to be able to do that. So, "exporting" them may be the only way to deal with it -- and not let them go and back into that society, once again.
Since they arrived on student visas, rescind those visas and the job is done. No need to make the case. There are plenty of people who are denied travel visas over far less.
Michael Savage does not pose a threat to national security yet is banned in britain.