It wan’t bending the cards.
My understanding is the defect in the cards was that the pattern on the back was off center a little closer to one edge than the others. After conning the dealer into sorting the cards for them the players could see if the cards were a high card or a low card by it’s pattern’s proximity to the edge of the card.
As the cards went through an auto-shuffler they never got misoriented when they were shuffled. The deck stayed readable.
