Deport where? These are US citizens. The most you can do is charge them with treason.
As for the ISIS recruiters on twitter and facebook.. bet most of them are run by FBI to catch such sympathizers.
There is a balance between individual liberties and security, the irony is these guys use the same liberties availed to them and use it against the country that provides it to them. If that guy did some of the things he did, in Iran, he would be dead long before taking any hostages. But here in the US, we dont prosecute someone for their views; we prosecute them for the actions ( though they can be harassed ). It is one of those ‘your liberty ends where my nose starts’ kinda thing.