I don’t have direct contact with Armed Forces or aerospace industry but I did hear having a proper US govt security clearance really helps with getting a job in aerospace. The problem is getting it costs a lot of $$$. That’s where USAF or USN comes in.
Since he already has BA, he might try getting into United States Air Force Officer Training School or similar program for Navy, try to get into a position that requires security clearance (not that he has much control over it…), and once he’s done serving, he can try to get a job at one of the defense contractors.
I was told if you have a security clearance, they are almost willing to train you on the job, because it’s hard/expensive to hire people with proper security clearance.