Navy & Marines work the same way; it's Federal-Law driven.

You get Military Medical (space-available) when you turn 60.

By the Way: my comments previous were for paid-drilling guys. If you are IRR, you need the 50 points a year to make it a "Good Year." If you only earn 49, they all go away, and the year doesn't count for either your 20 total OR 6 in the component.