Just out of curiosity and elderly man I know who is 91, has ALWAYS carried a .32 S&W revolver in his pocket, everyday and everywhere. He does not have a GWL, I tried telling him that he needed to get one just in case, his reply was "I have been carrying this same revolver in my pockets since the late 30's and no one is going to stop me now, I don't need a piece of paper saying I can"......On a side note even though he is 91 he can still shoot that little revolver VERY well for someone his age.
How much trouble would an old man like him get in if caught?
Depends on what happened. If he shot someone unjustified he would have problems. In most cases LEOs would have respect for his age and give him a pass with a warning.