Biggest bunch of BS I ever heard. The motor, the frame, most everything except the rotor(which could be carbon graphite) reflects radar. They were just asleep at the wheel.
Not necessarily. Most ATC radar are not able to see something the size of a bicycle going 40-50 MPH.
And it sounds like he was flying in between the buildings. A return like that would probably be filtered out as ‘ground clutter’.
Radar isn’t going to be very useful for small things flying at, or even below, tree level. Everything down there is ground clutter. It’s odd that people seem to just assume that there are sensor systems that can just capture anything and everything. There aren’t. At sea they might have a chance to pick it up but even then they might not. Ashore... Not likely at all.