Thanks for your advice/opinion. Appreciate it.
Just to clarify, we don’t randomly stick our hands in his food or his mouth. I’ve put treats in his bowl while he’s eating and I’ve picked it up to add treats to it. (Then mixed with my hand) He has shown no aggression or any type of agitation when doing this.
He’s pretty good with his commands for drop it/leave it and hand signals. There have been a couple of times on a walk where he picked up a chicken bone or a rib bone off the sidewalk. He wasn’t listening to the commands to drop it and I was afraid of him swallowing a chicken bone, so I reached in there and took it out. ( we had no treats with us on our walk to trade) He showed no type of growl or aggression. This has happened only a couple times that we had to open his mouth like that. We are working on that if it happens again. (Offering a trade) I was just making an example in my original post that we are able to open his mouth with food without him biting or Showing aggression. We don’t just try to take things from him randomly. There is usually a reason.
Super!! Sounds like you are doing everything I would do and the fact that you could get that bone out without a reaction says that you have a good dog and you've counter conditioned him correctly.
So I just go back to high value in small space with a human he views more as a littermate in the pack and he was saying "get away, it's mine". I think this is something that could have serious consequences but given what else you've said, I also think it's fixable since this was a one time event.
I would set up a crate where he can eat and get treats. Teach him a down and wait command. With supervision from you, help your 4 yr old give him his bowl of food while maintaining the Wait and then let him release him to the food.
Rules. Black and white. Always.