The usual advice is "just treat disabled people as people" but it isn't super useful because humans don't "naturally" treat anyone like anyone. Much of our social interaction is cultural and learned. So it's extremely helpful to give specific, actionable advice ("just tell your child to wave").
I have to admit to occasionally looking away, or doing other things mentioned in the article. It's not because I think disabled people are "worse" or because I'm an asshole. It's because I get a momentary "shit, this isn't automatic, what do I do" feeling, and by the time I arrive at a conscious decision of what to do a few moments later it's too late.
There is a lot of shaming of people that I think would be much better replaced with education. Most people aren't assholes. They just don't automatically know what to do. We can fix it by giving people specific actionable norms.