A couple of reasons. First, there wasn't room between the back of the cab and the cover to build a good hinge system that would allow it to swing up and clear. He would have had to build a hinge that moved it rearward first, then up to clear the back of the cab.

Secondly, when he flips it open at shows, the entire car will be opened up so anyone looking at it can get a clear view of the cockpit and all the airbag components in the bed. He is going to have no floor in the bed, so all the workings will be right there to see. If he hinged it the other way, a viewer would have to walk around back to see under the cover. This way they can stand right by the cab door and see the entire car.

Also, it just makes it a little different, like those '57 Ford hoods that opened up backwards.

Don