This seems like a potential violation of the Magnuson–Moss Warranty Act, which prohibits the refusal of warranty service for using third-party parts without proving that the third-party parts were the source of the malfunction. Assuming Apple will refuse to repair these under warranty, which they almost certainly will, this is effectively requiring the purchase of screens from Apple to receive warranty service. On the other hand it's somewhat debatable whether the screens or the OS update are responsible for the problem, but the screens were clearly working fine before the update.
Given that iPhones with OEM displays are apparently still working fine...isn't it pretty obvious that the third-party parts are the source of the malfunction?
There is zero evidence so far as to whether this is intentional sabotage of third party parts or not. However Apple has already demonstrated that they are able and willing to do this kind of thing i.e. with non-certified Lightning cables that also previously worked perfectly fine.
If there is a bit of code in the OS update along the lines of
if(DisplayID != GenuineApple) { breakPhone(); }
then it's obviously Apple's fault. But it's not at all clear yet exactly what's causing this problem and whether or not it was intentional on Apple's part.