Coworker of the cosplayer; I saw the whole thing go down. So perhaps I can clarify a few things I’ve seen brought up in other comments:

Wait a minute. The DoD is engaged, constantly, in active recruitment drives to meet its quotas. They advertise on TV, put out video games, and the NFL has negotiated with them to show their “brand” on one of the most visible media platforms out there - the opening of an NFL game.