I just keep coming back to the apparent fact that these things seems to be able to move very fast and mostly important, accelerate at extreme rates. This implies extreme inertia / g-forces. That implies no biological occupant aka drone. Okay. But the propulsion mode is SO very "alien" to me, that it begs the question... how?!?!
And if we all had access to that mode of propulsion what would happen? What is this mode? Is it nuclear like I think?
So if it was a new mode of propulsion I can see covering that up for one.
P.S., along the lines of cattle mutilation...
I was driving out by Pueblo Army Chemical Depot east of Pueblo Colorado in about 2010 and there was a herd of cattle in a field. I was driving my then dog Heidi and I through the lonely roads there. There were some cows balling and I slowed down to investigate. There was a cow who was alive, and with perfect square patches of skin about 3" square removed from her left side. She was making the noise and others were circling her. I DID suspect chemical testing. That army depot is supposed to destroy nerve agents there left over from older times.