What would the US Army of WWII done with him?
Ah, I guess you're longing for the days of one of the biggest liberals EVER in this countries history American.
Alright, if this was WWII and ole FDR was CIC I imagine...if we play the game its obvious you want to play....
Instead of interring japanese (and some italian and germans) we'd inter muslims (and likely some of just arabic heritage).
In this case we'd not be going after an ethnicity but an actual RELIGION, something that flies in the face of the constitution, so we would have ramifications from that point onward in this countries history that the government is free to enact punishment on people for nothing but their religious views.
Its a far more connected and knowledgable world now than in WWII. As such there'd be far more uprising within this very country with people fighting back as it'd become known pretty quickly that the government was rounding up its own citizens instead of the confusion that was there early during the WWII incidents.
Additionally due to a mix of that connectivity mixed with the fact that we are now not viewed as a big savior coming in to save the world but instead as the people that in some way have either started or escalated this conflict, world sentiment would be far, far greater against us then it would've been in WWII.
Along with this, unlike WWII, there is not an similar and yet VASTLY worse situation occuring in the enemy country (as there was with the actual holocaust) to make our action seem far more mundane.
Finally it would take a great deal of government funding to round up 2.5 million people, house them, feed them, and guard them, likely meaning war time taxes would need to be enacted for the forseeable future (which, unlike WWII, seems to have no reason to believe it'll end within a decade) or even greater amount of debt assumed by this country, along with troops needing to be removed from needed combat locations to domestic camp locations.
I imagine that's what would happen if this was going on with the WWII set up in place.
That'd be so much better.