I disagree with this line of thinking. JerryRigg tried to bend the LG G4 and the Moto X Pure Edition and couldn't.
I have an alternative thought that I think is closer to the truth. The issue is that when he bent the phone the first time, there were a number of irregularities -- basically he did tests that cracked the screen, as well as heated the screen, immediately prior to the first bend test. In this case, the phone was weakened; the screen was broken at petty much exactly the weak point in the case and the heat loosened up the glue that is also used to provide some rigidity. So, using his standard amount of force he bent the phone.
Of course, he was called out for the fact that he bent a phone that had already been damaged and, feeling like his integrity was being questioned, he wanted to prove he could bend the 6P. At that point, and knowing where the weak point was, he then used pretty much all his force to bend the phone. In particular, look at where his hands are holding the phone (in the center, near the weak point) and how white his fingers are (from the force he is using to make the phone bend). This is far different than how he tries to bend the Moto X, G4, and other phones -- on those phones his fingers are holding the phones at the top/bottom, not in the middle, and his fingers don't turn white from the effort.
Basically, most phones will bend the same way the 6P does -- if you do apply that much force. However, in the case of the 6P, it was the fact that he "broke" the phone already first, which made it easier to break then when you try to break an undamaged phone -- and the second point he put much more effort into bending the phone, than he does other times, because of the accusations the first test wasn't fair.