There is absolutely no cryptographic means of preventing a Snapchat user from saving a Snapchat image he/she receives. No matter what measures they put in place

There is absolutely no cryptographic means of preventing a Snapchat user from saving a Snapchat image he/she receives. No matter what measures they put in place, they will all effectively be security by obscurity. If the image is in RAM long enough for a human to see it, then it can be copied elsewhere. The fact that their current encryption procedure is half-assed is because they know it'll be security by obscurity no matter what they do, so why even waste time?. It doesn't make a real difference either way. They just want to prevent the absolute simplest attacks. They could have XOR'd all images with a 1-byte key and it would be equivalent, and still would suffice the business need.