It spins for a millisecond to have a chance of obtaining half a bit actually. It takes two clock calls to create a chance of getting a bit, and only if the bit pattern changed during that period.
I dunno Keccak, so I'll talk from a Skein perspective. If every millisecond you added the "nanoseconds" field with the Skein cryptofunction salt = mix(nanoseconds + salt + current seed + other Skein stuff), it'd be pretty darn random. (Apparently Keccak can 'sponge up' entropy somehow, but I don't know the mechanism that it does it with)
The output would at least be a crypto-secure PRNG. All that needs to be proven after that fact is whether or not enough entropy was being gathered from the real time clock.