MOV a "single instruction" stretches things quite a bit. It's more of a big family of instructions that happen to share an assembly mnemonic.
But if you look at the serious attempts to implement OISC, you'll find that the "single instruction" has so many parameters, some might think it might as well be a big family of instructions.
That was like one of my professor's version of Object Oriented programming. He would simply message pass to his undergrad assistant, Mark. "Mark, code up an X."
Reverse Substract and Skip if Borrow (RSSB) uses only one parameter and is supposed to be turing complete. I havent understood how it works, to be honest.
But if you look at the serious attempts to implement OISC, you'll find that the "single instruction" has so many parameters, some might think it might as well be a big family of instructions.