Earlier quoted context omitted.
It's a little bit different when the person had taken up arms against the nation, no? Should they get a court hearing? Probably. Is that practical, in some cases, if the person could be apprehended. Otherwise it would just be a pony show with a predetermined outcome, making no difference.
The right to a fair trial should not depend on whether it is practical.
Perhaps it would have been better in the specific case to first revoke the person's citizenship?