I don't know about the guitar that he is currently holding, but many country or blues musicians tune their guitars down a half step. If the guitar given to the President is in this tuning then that indeed would be a mighty fine sounding G chord. Which would be a good start to his wailing away at the the great standard, "Nobody knows the trouble I've seen." However I believe that this would be a performance that is mostly forced and contrived as Papa Bush has done his best to insure that Junior doesn't really have any trouble during his life. Must be nice to have a house to sleep in, medicine when you are sick and enough money to buy yourself an election or two.