OP, I understand, regret that you find the new age rules frustrating. I don't blame you, it is annoying. One of the best hitting partners I had all summer was under 20 years old and was on our USTA team. I would not have met him with the new age brackets.
My two cents.
Since coming back to tennis some years ago (and thus having exactly zero hitting partners) I set out to find guys to play the way I like to play: no such thing as a "practice" or "social" match. Singles play, all out, every match matters. From there I got one of my old tennis buddies back into it, got another friend that was out of it ... back in. And played club and USTA leagues with the main intent of building a deep Rolodex of players that are intense competitors, available when I am.
Over time the list of guys exceeds the time I would ever have available to play, and it is not uncommon to play with 5-7 different guys a month. These are guys I like, and I am open to hitting with anyone at our club or some other clubs.
Anywho, league play is a small part of my tennis experience, and frankly contains 100% of any negative component -- aka the nuts. I can pass on it altogether if I had to make a choice, that's how ambivalent I am about the value to my health and recreation USTA and club leagues are and have been. Was a house league champ, woot, bumped up (like a FICO score IMO ... who knows how it is really calculated??) And all that.
So perhaps this USTA age thing is a chance for you to change the parameters of how you enjoy this sport. Or go do something else with the time that is fun and where some bureaucratic 'authority' can't pull the rug out from under you like the USTA has.
How about poker runs in a 1962 356 coupe on Indian Summer days? Skeet and trap shooting? Cross country skiing (so much less dangerous than Alpine skiing as an adult), medicine ball catch, or as they say in New England, 'what have you?' Whatever is fun, who needs aggravation?