First off, that was not a whole cup of water. secondly no one is taking evaporation into affect.

Water boils at 212 degrees normally. I know my motor runs in the 240 degree range.

The valve was open as high temp, a good bit of that water was vitually boiling as soon as it touched anything. But there was no way that little bit of water would hydrolock and motor. I suck more than that up on a 5 mile trip when its raining