Assuming that the teacher credits the accusations of tower-tipping, etc., and realizing that "Someone told me to do it" can sound like a false excuse, I don't see what's so wrong about the word "annoying". Yes, it's important to make sure that bullying isn't going on, but sometimes little kids don't play well with others, and that can be annoying. I'd be annoyed if someone kept wrecking things I was building.
Could the teacher's word choice be calculated to give less chance of offending someone? Sure. On the other hand, she has to do something about the situation, and I don't think she's making a bad choice. She can't force certain children to let others play with them during free time on the basis of crying in a situation like this; he's not being excluded by the whole class, just a subset that he has apparently been credited with annoying by his behavior.
