I really don’t see where a school teacher gets to say what any student has on his wall. It’s a sticky wicket.
I could imagine porn or whatever. I don’t approve but it’s not a public
classroom. It’s his house.
The teacher doesn’t get to say what is on the kid’s wall, but the school may have a say on what is shown on camera. Zoom provides a whole range of backgrounds that can be displayed which prevent anyone from seeing what is actually in camera range, for those people who don’t want the world to see what’s in their house. Many of them are neutral and non-distracting.
Provided that the rule is applied in a content-neutral way, I don’t have a problem with restricting what is sown on camera/