OP - if the toy works, then take the toy. It’s a simple solution and it works. If your husband is worried about how his family will react, then that’s a separate issue. Managing your child’s needs should come before other people’s opinions.
The world has changed, I believe for the better. Disabled people, including those with severe learning disabilities, are no longer hidden away. That used to happen; it was wrong then, and it’s wrong now.
Autistic children with complex needs have just as much right to be in public spaces and do normal things as anyone else. My daughter, who is autistic and non-verbal, enjoys going out for lunch with her family. She isn’t always quiet, she sometimes makes noise, but that’s ok. We know what she can handle and we prepare. We speak to the restaurant beforehand and ask to sit somewhere a bit out of the way or in a booth so she feels safe.
And yes, we are paying customers too.
I wish my daughter wasn’t disabled. It’s bloody hard. She goes to a specialist school for autistic children where they work to teach her and her classmates life skills. They go out every day. Supermarkets, bakeries, greengrocers, garden centres, pet shops and even McDonald's. Learning how to navigate the world and build life skills matters, because that is the world they have to live in. I can see how much this approach has helped my daughter, and it makes her life better.
My personal opinion is that a random stranger’s right to a quiet meal does not trump my daughter’s right to be part of society. If that bothers them, then that’s their issue to deal with, not hers.
Things have changed. People need to accept that.
I suspect my opinion won’t be popular, so I’m dusting off my hard hat.