I couldn't see where it said that it was Atkinson that forgot. It seemed to give the impression that someone else was supposed to have done it, but it didn't really say.

Sorry, to say, but the article referenced does not give any new information. The data is lost and an attempt is being made to reconstruct the path of the huygens probe using the doppler shift of the signal picked up by several radio telescopes on earth. This require huge computational efforts which can take several months to be completed.

It was ESA's fault (no one is saying exactly whose fault in ESA). They created the command sequences for the Casssini/Huygens decent. They missed flipping the bit to turning on one of the two receivers. How can you forget something so important? NASA/JPL/ESA did this as a "joint" venture, so ESA had that responsibility for the Cassini programming at that point in the mission.