I don’t think it is man’s nature to physically abuse 10 year old girls and to sexually abuse 12 year old girls. It is the nature of sick men. Maybe this guy can go found a religion or something.
Unfortunately for these girls, this man was left alone with girls all the time. He demanded that parents leave the facilities and not watch practices.
It is among the most basic of animal-human natures, it holds both sex and power combined. It is a very powerful drive.
To deny its potency is to subject more generations of youth to such predations, harms and perditions.
Yes, as humans, enfused with G-dly souls, we are capable of surmounting such traps arising out of our basic nature. But in these cases -- coach-to-youth, because of the intrinsic animal-like nature of athletics (it's not the chess team for gosh sakes) -- the traps require strongly enforced particular rules of proper behavior, with a constant vigilance.
This is actually fairly common to allow the gymnast to concentrate on listening to their coach, and remove the distraction of the gym parent who feels the need to intrude and "coach" their child from the sidelines. At the same time, there obviously *does* need to be a way to guarantee that there are always two adults present, especially when/if one is male. The gym where my kid goes has LOTS of windows, is well lit and is very open all of which removes any notion of privacy.