No fear about hydrolock on, at least, our motors. The airbox is strategically hidden under the tank and pulls air in from a few gaps sandwiched between the motor and the fuel tank. Unless you've done the Airbox mod, the opening is really no bigger than the skinny side of a deck of cards. (yeah! That small). On top of that, the filter requires water to come up through the hole, and then up through the filter. After that, water that has pooled at the base of the velocity stacks needs to get sucked in. I'd have been more worried about hydroplane.
Though personally,I probably wouldn't have been revvin' it like he did, but I can definitely understand his frustration with riding though water like that. I get really pissy riding through sprinkler puddles.