Sounds like you’re the lawyer, here.
Is this something that can be decided by a Judge BEFORE any trial begins, as it appears to have an impact on his status and maybe the venue/jurisdiction (not a lawyer, myself)?
Would it take more than 5 minutes?
I don't do this kind of law, but, based on my reading of the law, if the govt chooses to bring this kind of proceeding, it would be separate and apart from any criminal proceeding, so it could happen before the criminal proceeding. The removal of citizenship would be retroactive to the date of naturalization, as if the guy was never naturalized.
Note that this is an entirely hypothetical discussion - while the govt would be allowed to use military tribunals if it stripped this guy's citizenship, it would not be obligated to do so, and the 0bama admin has already decided not to.