I am the mother of a disabled child who lived until he was 22.
He couldn't speak but this would have made him laugh - loudly.
I see nothing wrong with the performing arts. No matter who is involved.
If you watched it and laughed so as to make fun, that says more about you than I would want to know.
But if you laughed because they were obviously enjoying their own performance, to me that is just a heartfelt human connection.
Kudos to their director/teacher.