Because higher levels of testosterone influence the brain to optimize for things that are good for doing science.
We call that "pseudoscience" where I come from. In this specific instance, because you're wrapping a belief in the trappings of science to lend the claim credibility without the benefit of actual scientific inquiry. You might as well claim that your healing crystals work because they've been exposed to tachyon energy.
How do these studies explain why so many gay men go into hairdressing and fashion design ? Because society pushed them ?
To my knowledge, that has not been addressed. I am also unaware of any study that establishes a propensity in gay men to become hairdressers and fashion designers.
Your bias is showing...