Actually I agree with him. Let's say you encrypt a jpeg. You end up with a blob of bits that doesn't contain anything resembling jpeg data - the specific arrangement of bits that make what would be recognised as a jpeg file doesn't exist. It's recreated by decrypting the file - you make a new blob of bits arranged in the way a jpeg file looks. Technically speaking, the encrypted data is not a jpeg, but an input to a function that creates a new file which itself is a jpeg.

You and I both know that the encrypted data is only useful for generating the decrypted jpeg and in that sense the two could be the same thing, but I definitely see the sense behind his argument.