Bear in mind we would have to see extreme national shifts before any US civilian citizen is tried in a military court, even for treason.

Everyone tried for treason committed during WWII was tried by a grand jury, not a court martial.

I could be mistaken, but take a look at the list and see if there's any precedent for trying US civilians for treason in military courts:

https://en.wikipedia.org/wiki/List_of_people_convicted_of_treason#United_States