That’s why a common 777 and the redress will make it look like every other 777 from Delta or AA or whichever designation.
“JFK Control, this is AA 2471, could we get landing approach instruction?”
They find a scheduled flight and set their transponder accordingly.
They would have a higher chance of exposing themselves if they file a flight plan as a U.S. carrier. Nothing to keep them from using a foreign registry and saying it’s a G5 or similar aircraft. Same airspeed, range and nobody knows the difference. Plan your arrival under the cover of darkness and never land...