Not even slightly surprising. Resistors in paint cans full of oil has been the favorite method of building high wattage "dummy loads" for RF and audio testing for years. Just a case of "everything better be working before you pour on the oil" - repairs are not going to be fun.
If they had it working under water, THEN I'd be amazed. Oil is no big deal.
They actually did try it in distilled water first. It worked for about 5 minutes. Amazingly, nothing was permanently damaged.
I wouldn't expect a few minutes of water to do any damage. More of a case where I wouldn't expect it to work. In older electronics the impedance's tend to be lower (and digital speeds slower) so water didn't have nearly as much effect. At the extreme, it wasn't unusual to take a scrub brush to someone's amp. We'd wash it down in the sink to get rid of the dried beers and dead bugs from years of gigs before working on it. These days, I've had pieces of consumer electronics that were wiped out by minor water spills that wouldn't have been a big deal a decade ago.
The increase in system impedances has also led to a lowering of system noise immunity. Progress is a wonderful thing.