There are several things like that in Fedora, which is already a good reason not to recommend it to first timers. They most likely won't know or care about nonfree codecs, they will just see a broken machine. Linux Mint understands that as a use case and has a "magic make it work" checkbox during install.
That all being said, I run Nobara and love it, but i wouldn't recommend it for new people.
I haven't done any work for the military but i can say that all the legacy systems I've worked on were because the specific software they need was written only for Windows 98 and the developer or company that created it is long gone. Keeping it going is a chore but switching to literally anything else is out of the question.
I could see for military applications that having the known quantity of a working piece of software that isn't changing anymore and can be swapped as an entire unit is an advantage, especially if it doesn't touch the internet in any capacity. But eventually you run out of people who know what to do if any changes need to be made.