I don't see anything inappropriate. She's cuddling her adult son who has severe disabilities.
If he was 2 years or 6 years people would find it cute or admire her for comforting her child, it's because he's a grown adult and most older teens or adult men don't cuddle with their mother.
When a person has a chromosome disorder some like to be comforted, some don't. My 17 year old DD who has a chromosome disorder doesn't usually like contact like this however there was a time she was upset and she lay on me and I rubbed her hair, it was a fantastic moment because I have never had a hug or kiss from her ever as it distresses her, I sat like that for ages enjoying every second because I knew it may not happen again, we were in public and tbh if I had been in a bikini or snow gear I wasn't letting go, unfortunately there was a woman who felt the need to suck her teeth and make an ick facial expression.
Sometimes just let people do what makes them happy and relaxed without passing remarks about them, we don't know if he was upset or being calmed. We also don't know who she brings with her, she could have a team of people who prefer not to be photographed.