Isn't this all speculation by everyone? My reason for such speculation is that if the Oumuamua was actually a probe, the little information which we can observe from it (speed, size, trajectory changes) is plausible in terms of our current technology and understanding of physics. What was seen by the Nimitz is not.
We know barely anything about Oumuamua, clearly not enough to decide what kind of object it is, even less about the Nimitz encounter and yet, based on two nothings, you are feeling confident enough to say that the would be civilization that build 'Oumuamua' is less advanced than the would be civilization that built the Nimitz object.
Jumping the gun a little bit are we?