That does sound like resource guarding. Is there possibly a dominance issue as well?
Someone on YT recommended the book "Mine" to help with resource guarding, if you want to check that out.
Other than that, I would recommend the usual for bad behavior. Practice with him on your lap and your husband leaving the room, and reward him if he is able to restrain himself. Keep him on a leash for this exercise so you can restrain him for bad behavior. You can also give him a special "place" he is supposed to go to on command, and train him to stay there while guests leave. Gentle corrections, positive reinforcement for desired behavior, and build up gradually. Good luck!
