depends on how you orient them tbh
if you manage to prop up either of them by using some plastic thing then yeah they're also doomed
but since we're talking about just the three in general, then due to gravity and physics scissors and paper would fall flat on their surface — paper would likely survive due to the thinness, while scissors would just get squashed but still keep most of the original shape
but yeah, as you said, rock would get crushed no matter what
