But I don't think children ask questions about what they see because they think it is incorrect.
They ask about it because it is unfamiliar, and they want to familiarise themselves with it.
Education could certainly help with that, but there is no way to expose a child to every sort of disability or difference they are likely to see in real life, which means they will always run into people who have features they are curious about. And when children are curious, they ask!
I do think it is unfortunate that children's questions do upset some people, but I do not think this makes the questions rude, nor do I think children should be told to assume the person will find them rude (because a lot of people don't).
I do think its important to teach children to gauge whether the person is happy to be talking to them or not, and if not, then to respect that and leave them alone.
Again, this has nothing to do with the child's 'rights' in my view, and I find it abhorrent when people use 'rights' to basically say they will do whatever they please.
I guess I have more experience with people who hate having their obvious differences avoided and skipped about in conversation, and find this extremely alienating.
There is no way to please everybody in this situation. Some people don't want their disability mentioned and find this upsetting, others don't want it deliberately avoided as a topic and find this upsetting.
I don't believe a blanket rule of behaviour works in this situation.