Code is code my dude. If an LLM can turn English into Python, there's really no reason it can't do assembly. Assembly is not magic, it's just code that humans find difficult to grok. LLMs, it would seem, don't have the same kind of trouble understanding assembly that humans do.

Have you ever compiled something by hand? You should try sometime, it's an illuminating experience. Humans find it hard because you have to remember a lot of details while simultaneously paying attention to a different large set of information while also generating instructions. It's tough, but not impossible, it takes humans a lot of time and effort. How might a computer fare if it could remember everything and pay attention to multiple inputs and outputs at once? That's what an LLM does.