I have done exactly that, calling for my sons who were hunting elk, at times when I was not a WA State resident. I came over during elk season to keep camp, call for them and help pack meat. It never occurred to me that I would need a license since I was not hunting in the sense of being able to kill anything, and did not carry a bow nor firearm. I never even thought to check and am glad that others have checked with wardens.
FWIW it is a particularly pleasurable way to spend time in the woods, helping other hunters succeed.