“It had to have a mass to be picked up by the Nimitz radar.”
Mass? No, not theoretically.
Physical, yes, at least it has to reflect radar waves.
These is a contradiction on the face of basic physics, but I think the answer is deeper in the physics problem if in fact this is “real”.
Zero Point propulsion (as it is explained) does not contradict basic physics, as it captures a piece of the local spacetime and moves over spacetime, not through it as rockets, etc do.