I know that this won't be a popular message in the midst of the current knee-jerk hysteria, especially on this thread, but as SLF, I am extremely disturbed by the idea that regulators and airlines seem to be falling over themselves to ensure crew are never left alone in the cockpit.
What that amounts to is an unequivocal statement that the aviation industry views every one of its FD crew as an unacceptably high safety risk if left alone.
Since they are there to protect me, and since I am absolutely positive that one of the FD crew, suitably motivated, could crash any aircraft they wished, whether or not they were alone, that is very, very worrying indeed.
Personally, I think it's yet another case of being seen to do something easy for no good reason except to appease the baying masses, but, if the concern is justified, I'd rather not be flying in that world.