Postponing the obvious quote for the moment, the question with any backdoor is what's to keep the bad guys from finding it. (Okay ... the other bad guys. Picky, picky.) If something is known to have a backdoor, the hackers will do whatever it takes to find it. Breaking in to some manufacturer's system, bribing someone, or just brute force - once they find it, they know what it is on all similar systems. If anyone has a backdoor then the supposed protection is meaningless.
The quote? Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety. - Benjamin Franklin