I would conclude that the train in question was under remote control operation. The initial pictures I saw showed 2 GP9's with a slug in between off the tracks. Those would units involved in yard switching, not mainline running. That would concer with the comment in the article about employees being positioned at the leading end of the movement. Thus, it would be not out of the ordinary for some cars to not have had their brakes hooked up and active if it was involved in shuffling cars. I imagine to an extent, the order to limit train lengths will put a bit of a damper on the efficiency of the switching. Don't know that having all the brakes hooked up and working would have helped. It appears the operator did not have a proper view of the leading end of the train and it ended up sideswiping a passing train.