No. Turning gay is very easy. All it takes is seeing two dudes kissing and you're done. Maintaining your straightness requires constant vigilance.

also by that logic there should be no gay or trans schoolchildren as homophobia and transphobia were in the curriculum way before queer people began to be accepted-ish in the society

We can't take that risk

Fucking seriously. The goons most likely to respond to this kind of propaganda are also usually the parents of the kids who aren't listening to a damn thing the teachers say anyways.