Depends on how you train and how/if you compete. I've had students in their 80's doing Judo. But they weren't doing shiai. They stuck with careful uchi komi and sometimes some light and easy randori.I'm getting on in years, though and my joints really aren't the greatest. I've heard that judo is really hard on you
Do you mean if they don't have anyone older than 30?Go watch a few classes and talk to the instructors and students. If they don't have anyone younger than 30 and more than 10% of them are sporting joint injuries, you might want to look elsewhere.
Peace favor your sword,