A boy competing against other boys would be disqualified for performance enhancing drugs. Otherwise, every boy would have to take performance enhancing drugs to be competitive.

That’s the answer. No gender categories. Everyone competes evenly. No Women’s tennis or Women’s soccer. Well, really no women playing sports competitively then.

Not being allowed to compete against boys is a consequence of trying to be fair because the rule was designed to prevent boys transitioning to girls not to be allowed to compete against girls due to the physiological advantages. Taking testosterone is a performance enhancing drug, and he should be disqualified.