I've known this co-worker for 20+ years. He's a good guy and a straight-arrow, but he may have been trying to beat that traffic light coming out of the Mall (it's known for long delays as it intersects with the main drag). Since it was dark, he was probably focused on the light and didn't see the water (and may have hit it hard, sending a wave over the hood). If the_same_mountainbik is right about intake ducts below the headlights, then maybe the engine did ingest enough water to cause hydrolock.
But it still surprises me for two reasons:
1.) I've been driving for over 30 years and I'd never heard of such a thing! Water ingested into the engine???
2.) You'd think the Germans would've done their typical "over-engineering" of their vehicle to protect against this somehow. After all, you're building a low-clearance, high-performance vehicle and selling it to people who like to show that power off. If driving through a modest dip in the road (like my co-worker did) is enough to blow an engine up, you'd think this problem would be widespread and well-known by now.
What about the possibility the engine stalled to protect itself and the water could've been manually expelled to fix the problem? Before you say "How could the engine respond that quickly?", watch that "This Old House" episode where a table saw blade, rotating at full speed, instantaneously stops (and drops below the table top) when a hot dog (simulating a human finger) touches the blade ... leaving the hot dog unblemished!