You might be right. I think it depends on the caliper design. Even though the shop my friend used, installed them the same way as the picture, his pads did not rotate on the pin and fall. When we got back to the shop they were still in the caliper the way the shop had installed them. This was a number of years ago, I think he was riding a K1300 BMW.
Interesting. I didn't see the crack. Admittedly, I looked no further after seeing the caliper wall worn from the rotor. Either way, this is a costly adventure that could have had life changing consequences.
I don't believe the pads would necessarily fall out. As soon as the brake lever was squeezed, which might be even before the motorcycle was moved, the pads would be locked together with considerable pressure. Also, the rotor appears to have worn into the caliper body. It could be staged, but a rider would have to be willing to allow his caliper to be damaged, and that would be an expensive joke. What to me does argue for staging is how much noise that rotor rubbing against that caliper would have made while wearing away that much metal. But having done things nearly as stupid, and channeling Crabballs ("you can never underestimate the power of human stupidity and determination"), I think it's possible this is the real deal.
Not only is there a crack in the caliper, but also the rotor has eaten into the caliper and vice versa.