Well, that's what I'm saying. First the glass breaks, then the frame bends, not the other way 'round.
There have been thousands, if not tens of thousands, of iPhones that have or had broken screens. And yes, most all were dropped--probably a lot more aggressively than the OP indicated about this iPhone.
If your theory was valid then there would be bent iPhones all over the place. There isn't, or at least people are not reporting about it--at least not in connection with broken screens. I would think that would be such a surprise there would be plenty of reports.
Indeed a cursory google search turned up a few bent iPhones. But, interestingly, they did NOT end up with broken screens.
So there is evidence to suggest an iPhone can certainly be bent with enough force, yet the glass survives. That is precisely what many have been saying happened in this case.
After reading about a few bent but not screen damaged iPhones I am convinced that was the case here: iPhone had been previously subjected to a much greater force than this 4' drop, bent, and then the 4' drop pushed it over the edge.
Now I personally don't think many people would not examine their iPhone after that first incident. So I still think the friend, if there was one, was not being completely truthful.
Michael