from my experience i can tell Jump Shot is very hard to keep on a high level for older dudes.
I think that was just random. In fact, a few of my players have lost every skill *except* jump shot! This guy
(10282407) even had decent shooting ability into his 50s. His jump shot finally fell to awful last season, but keep in mind that the rest of his skills have been atrocious (1) for a very long time.
Plus I've had a couple of players in their late 40s get pops in jump shot and hold onto it for a while.