Teaching indisputable facts like 1+1=2 (which isn't even true if you're working in binary btw) is a vanishingly small part of our job. A much bigger part is relentless, quick fire decision making about how exactly to respond to every single misdemeanour by every single child in every single situation. What would be an over-reaction, when does a de-escalation actually hamper the learning of the other kids in the room, whose version of events is closest to the truth, what sanction would be fair and so on and so on.
In all those scenarios there are a range of broadly "sensible" approaches, and a number of unfair and/or counterproductive reactions. Same with RSE. It's broadly "sensible" to keep kids on track with what they're meant to be discussing, and by and large to swerve potentially inflammatory subjects in a whole-class setting.
Of course some schools/teachers are getting this wrong, unintentionally or otherwise. This whole thing needs to be looked at properly on a national level. But in my experience, these incidents that are rare and extreme enough to become newsworthy are absolutely not representative of how most schools approach RSE.