I think someone didn’t understand what you meant and downvoted or downvoted because you didn’t define ‘z’ and ‘x’ and so on, but I know what you mean and you’re correct. This is another way of looking at it that is completely right.

p(x) for all these images under a CIFAR-10 world is basically 0, but your CNN is not computing that or factoring that in and is just assuming the input images are good images, then estimating the probability of airplane vs. bird for these nonsense images given that they are not nonsense images and given that they come from the same pdf as CIFAR-10….. which is a very very false assumption!