Ok, I think you're right and the lawyer is confused. He quotes RCW 77.12.047(1)(c). This states
Note the "That may be used to take". If you are hunting with a bow during bow season and carrying a pistol for protection, you are not hunting with the pistol, you're carrying in accordance with other law. If you were to be hunting with a pistol during bow season, then you would be violating this law. It's not a matter of preemption (RCW 9.41.290) but one of lawful carry while conducting lawful outdoor activities.(1) The commission may adopt, amend, or repeal rules as follows:
(a) Specifying the times when the taking of wildlife, fish, or shellfish is lawful or unlawful.
(b) Specifying the areas and waters in which the taking and possession of wildlife, fish, or shellfish is lawful or unlawful.
(c) Specifying and defining the gear, appliances, or other equipment and methods that may be used to take wildlife, fish, or shellfish, and specifying the times, places, and manner in which the equipment may be used or possessed.
The law he's quoting shows that WDFW can enact law on HOW you can HUNT and FISH, but not whether or not you can carry for personal defense while performing those activities. He even says that the courts agree that the hunting laws don't "excessively burden the right to bear arms".
I think you need to discuss this with him further to get clarification, but it sounds like he is saying that you can carry for protection AND WDFW can regulate the method and equipment used to take game.