Personally, I don't think they'd want to mess with that aspect of it. With the (frivolous) lawsuits Disney is facing in regards to the program, disabling the
DAS users from grabbing 'normal' fastpasses is in a sense unfair, and would actually give the lawsuits ground. In its intended format, the DAS is saving your spot in line, and you do something else like watch a show etc. You are still technically waiting for your ride, though not physically in the queue. A non-DAS user is physically waiting in line for that ride and can still grab a FP for something else. I'm not a lawyer, but THAT would seem to not be equal. I get that the DAS is essentially a FP in functionality, but at the root of it, eliminating the use of real FP from DAS users would by definition, put DAS users at a disadvantage compared to the average park guest. I believe the scanning of the tickets is to ensure that there are not multiple DAS cards being grabbed per family, and that each ticket can only be scanned to one card, eliminating a lot of abuse the program currently faces.