Being double vaccinated means you are at far lower risk now than unvaccinated teachers - especially those who cannot be vaccinated due to ttc. So it is a bit of a pisstake to start telling unvaccinated people they need to be prepared to accept a higher risk than you are currently experiencing.
If masks are so useless / unnecessary then surely they should be getting rid of them in shops, pubs, churches etc on the 17th too. But they are being kept in those places, so clearly this isn't about following science so much as pandering to public opinion.
I say all this as someone desperate to get rid of masks. I'm happy to take the risk for myself but worry about what it will do to spread across the country if covid is allowed to go largely unchecked in many (if not most) schools.