From what I've seen in job descriptions for various defense related positions Ada seems to be written in as a small "nice to have" and makes me imagine most of it is maintenance or being replaced (probably by C++ too lol)
Not much Ada was written in the first place. The reason you see it in job requirements is because inertia and it's easier to slap those three letters in there than it is to try to explain to someone that there is no reason to require it on the job postings. Imagine if a bank listed Cobol on every single tech related job posting, that's basically what defense contractors are doing.
