Ive never bought a 1 day pass online so i could be wrong, but if they are like any other barcode I've ever seen....they usually have the numerical code under it to be punched in manually if the scanner does not work. It shouldnt really be a problem to enter the code to prove its valid.

Side question: Are the barcodes unique on all the 1 day passes? IE: Could someone in theory buy one, and keep photoshopping to change the date and re-print it over and over? My guess is thats what the agent thought but seems like a HUGE leap on their part to refuse access without any proof.