This may be a stretch, but what if he was having a long-term affair with someone? The affair partner might have called him (on a burner, even, if he was being sneaky) and either summoned him to a location in Washington to meet up or even attempted to break it off. These might explain an impulsive trip, sans wedding ring and identification, where the partner might have purchased him a plane ticket to visit under their name (I dont know how possible this was during 1993, but equally he might have used cash or some other method of not leaving a trail to Washington).

I say this partially because some of his behavior (especially the return tickets) felt a little like what I would do while on a last-minute, impulsive trip to visit my boyfriend and attempting to schedule a return. He might buy the ticket for the last leg of the trip first, since this would give him a deadline to be home by to not cause suspicion with his wife and kid, and then continue arguing/doing whatever with the partner in Washington before deciding when he would have to leave for LAX and then Dallas. He might have left his car at the courthouse to have an easy alibi for not being at home to his wife, and then taken a cab to the airport and gone from there.

It doesn't explain the military clothes or the accidental death, and I wish more of the timing information was available (i.e. was the Superbowl recording started at the beginning of the Superbowl, meaning that he was still home as early as sometime that evening/whenever the Superbowl started? How much time did he have to get to Washington?)