BMW cars have been aquaplaning off the road like that for decades, its about time the media admitted it.
I would have thought that the aquaplaning was caused by the depth of the water, the type of tyre fitted to the car and the driver having his foot planted at 120mph in dangerous conditions with the traction\esp off rather than it being a BMW. The M135 has Michelin Pilot Super Sports as standard, and they are pretty close to a track day tyre and are not good a clearing water, but are fantastic in the dry\damp (not full wet). These tyres would have also helped it with it's dry lap time, maybe 1 sec per lap faster than the Bridgestones on the Golf...).
I looked very closely at the M135, and was tempted but the Golf won me over as the sensible choice out of the two.