He obviously had permission to wear the uniform. I don’t really have an issue with it. All of this relates directly to his job in the Army. I may disagree with what he did, but he has the right to wear it.
“Directly?” It is a stretch to even say that this indirectly relates to his job. I doubt he wears the uniform while at his present job.
In my experience, a particular situation determined that you either wear the uniform or you do not. There is no “right” to wear it. Never heard of a “uniform optional,” situation.
The son of a bitch was “out of uniform” while he was in uniform.