The loops on the hinges are only half-closed, which results in the top half of the case having to be completely removed when it is opened, as it will leverage itself to the bottom half of the case and bend inwards! This lack of proper hinges leads to alignment issues when trying to close the case.
Also, there is considerable slack on the butterfly locks when they are in closed position. This actually gives the case enough slack to make the two halves of it moveable when locked together.
Summary: If you're transporting the Poly D on your own by car, then the case should be OK, as it protects the unit. If you're lugging it around town on foot, then I fear the locks could actually slip open. Better get an extra strap, or buy a better case.