He may be leaving Ireland but he's only on bail. He must return for the appeal and do his time if rejected, possibily in a Federal pen in the US if there is a reciprocal arrangement. If he doesn't return then he'll face extradition proceedings. He can contest that but I dare say there will be little sympathy from the US authorities.
Whatever happens he now has to face a nightmare of lots of legal fees and hassle.
He will definitely need a drink after that little lot.