i dont think requiring guns to be in a case during transport would change a thing. Your talking about criminals that are poaching. having to put the gun in a case isnt going to stop a criminal. if they are breaking the law to poach, why would they worry about putting the gun in a case? or like Rob said, they could put it in a case, take it out, shoot an animal, and put it back.
All this would do is inconvenience law abiding hunters.