We were told by two different NROTC units at selective schools to strategize and place a safe school as #1 on their apps in the event that they didn't get into their selective schools, then the safe school is still there. They recommended this based on the fact that changing schools was not a problem if they did get into one of their selective choices and that both of the selective schools' unit did not have a max limit on the kids that could come in. I'm guessing that's because their acceptance rates were single digits or close so they didn't have to worry about a max.
Good for your son about the recruitment! Athletics do have some pull with admissions.
Good luck.