Stupid. Why the before 21 BS? Just make it simple, compete in your birth sex or a new Open (Or “It”) category.
That would be “transphobic” ... the mutilated, and their simps, would be whining for the waaaaahmbulance.
I’d make it even simpler: compete in your sex. “Birth sex” is a redundancy. ;’}
I’m a very much third rate athlete. BFD. I don’t go whining about it or trying to screw up the women’s competition. I EARNED my middle-of-the-pack finish.