OK, you convinced me.

But we're giving an awful lot of credit here to MP and FFC if they thought this whole "why was Mike wearing his uniform?" question through the way we all just did.

Most viewers of the film were not and are not as familiar with the details, timeline, nuances of character etc., as we here are.

To most people, you show a guy in a movie in a military uniform. it means he's in the military.