Actually, I don't think that anyone is asserting that Corbett failed to transit the c/p or went through without getting scanned by AIT. I think the assertion is that he approached the c/p, put his camera in the bin, and removed the metal object after he was off camera, then replaced it in the pocket before retrieving the camera. This is entirely possible and plausible, though I don't see any evidence that he did this.

An unbroken video of one of those c/p transits, showing him putting the metal box in the hidden pocket, going through the AIT without alarming, and removing the box on the far side to show the camera that he had it on his person the whole time, would prove his assertions and shut up most of the criticism of his video.

Those who pull out the BS assertion that he's "showing the terr'ists the weakness in the system and helping them to plan an attack!" will simply be infuriated by it, of course. But then again, those folks actually believe in the security value of ignoring elephants in the room and penalizing those who ask, "What's with the elephant?" so you can't really expect rationality from them.