I read that entire thread and am puzzled by the fact a game warden's jurisdiction includes "safety" separate from DFG matters. That is, nothing to do with game, hunting or fishing? Also that he was not called in to assist or aid police in some criminal action or search.
As that thread plays out, it becomes apparant he probably had more reason to be there (because of his suspicions of game being taken illegally.) However, if his sole reason was for "safety" as he said, and not in direct violation of any game laws, I can't see him enforcing that and getting away with it if the matter was pursued. Now if he would have said he was there because he thought the loaded gun may be for taking game, violating a game rule, that would make more sense to me.