For comparison, I inverted the image in the OP’s link. It doesn’t look any more natural than the original.
I haven’t looked into this area previously, but it would seem very easy to have the image generated by these machines, and if necessary, any stored data, distorted without data loss and in a manner that eliminates normal fears regarding privacy. You don’t need to know the exact proportions of anyone to find hidden objects. And you don’t need much detail to do comparisons against prior images.
Also, does anyone know if there’s been a successful hijacking since we locked cockpit doors?
So far as I know, there hasn’t been a successful hijacking since the moment the planes hit the World Trade Center. United Flight 93 didn’t have locks on the cockpit doors, and it still wasn’t possible to hijack it. It was possible to cause it to crash, but you could do that more easily with a bomb (and no, the TSA doesn’t stop people from getting on planes with bombs).