The dog sounds unsure and fearful of the situation.

If you want Butch to accept your son as part of the household I would recommend having him to all chores with the dog, like walking and feeding, etc. Step back from being the dogs friend/leader and allow your son to step up and bond with him.  

In the beginning tell your son not to try to pet him or baby talk the dog, be confident and calm with the process and the dog will warm up to it as time progresses. Also practising o.b. while walking will help strengthen the dogs understanding.