The US military is big on equal opportunity. Deaf people should have the same equal opportunity as everyone, which means serving in combat units and the ability to hold command positions in combat units. If we can’t guarantee EO, then we’re discriminating and we might as well replace “deaf people” with “women” in our arguments.
Tons of civilians serve their country by working for the DoD or Dept of the Army, etc. They’re not soldiers, but they’re working for the military.