Dogs don't reason from cause to effect. He didn't think, I'm going to jump on Robert and hurt him. He didn't know he was going to hurt Robert. He just wanted to move from HERE to THERE. And THERE happened to be Robert's back. So when Robert smacked him, the dog thought, WTH? Why did Robert hit me for no reason? So in self-defense he gave Robert a good cussing out. Perfectly natural. And to his credit, he did not bite. He respected Robert's seniority. That's good.
Now, what to do about it? The dog (sorry, I forget his name) is somewhat, kinda borderline dominant. (At least!) My advice is, make sure he knows his place. Literally, his place is LOWER than the humans'. As in, he belongs on the floor, not on the furniture next to you. He should NEVER be in a position where he can get HIGHER than you by putting his paws on anybody's back, neck or head. That says he's the boss. Not good! The pack leader gets to bite. And he doesn't. He should never think it is okay to take human flesh between his teeth for any reason. Ever.
Now, what to do about it? The dog (sorry, I forget his name) is somewhat, kinda borderline dominant. (At least!) My advice is, make sure he knows his place. Literally, his place is LOWER than the humans'. As in, he belongs on the floor, not on the furniture next to you. He should NEVER be in a position where he can get HIGHER than you by putting his paws on anybody's back, neck or head. That says he's the boss. Not good! The pack leader gets to bite. And he doesn't. He should never think it is okay to take human flesh between his teeth for any reason. Ever.