Also, not everyone knows or belives that the half-cock notch should not be used as a safety and I've seen several people carry 1911's that way.
Yeah, I know not everyone believes it, just like not everyone thinks a gun should be carried loaded, never mind the carrying condition. I have a "1911" (old Auto Ord, so I consider it more a gun that looks like a 1911 . . .), and I broke the half-cock merely by fumbling a thumb-cock; the force of the mainspring was enough to break the half-cock notch.
A lot of drop-tests, usually on the muzzle to test the inertial firing pin, are conducted some number of feet above a concrete surface; I suspect a lot more impact energy is in play, under those conditions than a mere hammer-drop.
I recommend against dropping your gun under all conditions, but dropping a gun on a partially-cocked hammer is not a good idea, and in light of the various safety features of the 1911 that are essentially negated by carrying on half-cock, it's . . . still not a good idea. At half-cock, the gun is less safe than at either full-cock or decocked, but you still have to cock the gun to get it into action; even if it is "safe" it still doesn't make any sense.