By that logic then PHP itself is also assembly because someone could make a machine that executes it natively. We might as well throw all distinctions away if we go down this road.
I'm not sure if I understand what you're trying to suggest. Indeed, someone could make a machine that executes PHP natively. It's a Turing-complete language, just like C++ or x86 assembly for that matter so it should be possible to build a (weak) universal machine that executes them directly.
My point is that what someone could create shouldn't have any bearing on the discussion. They are using c++ as an intermediate language, fine. Just because we could make a machine that executes it shouldn't alter that distinction. We can still call that compiling, but hypothesizing new machines doesn't help.