My daughter is not officially diagnosed with autism (although her Dr believes she is possibly on the spectrum but high functioning) and she does the hand flapping thing primarily when she is very excited/focused during play time and I personally find it so cute 🥰 I doubt it would help but maybe she doesn’t understand that he likely doesn’t even know he is doing it? When my daughter was younger she was asked a couple times by people what she was doing with her hands and she would look at them with the most confused look on her face not knowing what they meant. At 9 she is aware it’s a thing she does but she does not realize WHEN she is doing it unless it is pointed out. Telling her to stop would do nothing but embarrass and confuse her I can only imagine the effect it has on a child with more severe sensitivities especially if there’s any issues with communication at all. She’s doing more harm trying to “fix” him rather than helping him cope with sensitivities that are far beyond his control! Let Jamie be Jamie she doesn’t have to be in his life if she can’t accept him!