This scratch test does not prove anything. The tips of keys are made of a soft metal, that can't even scratch window glass, let alone any glass made to resist scratching.
The only part of a key assembly that MIGHT scratch glass is the sharp edge of the keyring itself, as its made of steel.
All this does is proved that the Droid glass is not going to be scratched by the soft metal of keys and coins(American coins all have a hardness under that of window glass as well). Which should already have been pretty obvious.
Do NOT forgot a screen protector because of this. Other things have their way of getting in your pocket, and it only takes one scratch.
Until someone shows me sand or dirt with tiny pieces of rock it in it rubbed against the screen, screen protectors will always be a necessity of scratch free pocket transport.