The most interesting stat is the cat 1 guy who averaged 271 w and did 53:33. That's a CdA of below 0.2, which I think is impossible for a 70 kg guy. Heck, I did 280 W at the State TT last year and still only averaged 24 mph. I'm only 4 kg heavier and have been as low as 70kg before the male menopause set in.
I think there is something wrong with the article. I'd guess that Roessingh is closer to Levi's size than 70 kg. Else his Powertap needs some serious calibration.
The numbers for Baumann and Busche are pretty much in line for a guy in the drops and in a very aero position.
One can often go faster in the rain, cornering is a different story however.
btw, there was an ABR TT on the same course the next day. It was much windier and times were significantly slower, afair.