How to stop a child who is severely affected by asd mouthing all objects?

I am aware that this is a sensory and explority activity but he spends all his time doing this. I have also thought he does not know what else to do with the toys objects. I have noticed that when he is doing something he enjoys he does not mouth objects and appears more in tune.I am unsure if I should attempt to stop him or try to reduce it. I would be gratefull for any advice.