>he is still in the Navy in another role, where hopefully he can excel

That’s not how the Military works. The US Military operates on an “up or out” model under Title 10 US IS code 1407 where you have to meet promotion requirements within a very tight window (usually within 2-3 years) or else you hit your retention control point and are separated from service. A single bad yearly evaluation can mean you do not promote, and are shown the door. A total loss of an airframe due to pilot error is not something you’ll bounce back from.

>you don’t sign up to be an F35 pilot, you just sign up for the Navy

While this is somewhat true, it’s not exactly accurate. You don’t go down to the recruiter and get a contract explicitly stating you’ll be an aviator; but most pilots join the navy with that being the goal. Once they pass through their assessments and qualify for aviation they get incredibly specialized training which does not transfer to other naval career paths. It’s not like an aviator can just slide over to a SWO job because they get grounded.