How do you have secure encryption with proprietary backdoors? Maybe this will wake people up to only using open source operating systems.
Which they will. All they are asking for is some form of key escrow; which can (and has) been given a reasonable security definition.
The problem is that secure implementations of key escrow are much harder; and (given the amount of use the escrowed key will get), certainly going to be broken in practice.
OS security has limited impact when other subsystems, not in control of the OS, run on the device.