I am not defending his actions in any way, but how many times have to put your hand in your pocket to see if you had something with out looking at it? Then you you go to use it, it wasn't what you thought it was. Maybe he checked to see if he had license and felt them there, went out hunting, found the buck, went to fill out his tag and discovered it wasn't the right on. Failure to plan correctly isn't considered poaching, just plain stupid!
Your analogy is not a good one. Forgetting to put something in your pocket for later use is just a mistake and maybe a little dumb.Forgetting to buy your license(yeh, sure he forgot) is a violation of the law. Being stupid isn't a violation. Breaking the law is.