Interesting article, and good to know, but a few things stand out. I am always suspicious of a "news" article that is full of leading questions. In this case the "who are they protecting" string, with leading answers. While fine in an editorial article, his is a hallmark of bad journalism . To move on he mentions stickier tires, smaller wheels, and a novice driver as the contributing factors. The smaller wheels part is the one that gets my attention. I'm curious about the size of the side wall, as the percentage ratio has a great effect on sidewall flex, which could have caused "roll under" at the front corner of the car. The last thing - novice driver------------ I remember seeing film of the hatchet job done on the Jeep by consumer reports showing the rollover potential of the Wrangler. They had attached servos to the Jeep so that it could be remote controlled. They then took it through a "J" turn" at 40 mph and sure enough, the vehicle rolled onto its side. Jeep, after seeing the video and to defend its reputation had a human driver take the a similar course at the same speed. No problem even at 5 mph faster. The difference being the human feedback loop being able to correct for the slide and keep the car on course. Here we have the report a novice driver being unable to correct, not having enough experience to know the proper steering input for what (s)he should have been feeling through the seat of the pants and the steering wheel.
Many of us on the forums have been through the Octane Academy and know how the car slides. Although I personally won't use my car in any kind of competition (that's how you break stuff!) I wouldn't hesitate to use the Fiesta ST for any competitive event with no worry about putting it on its side.
YMMV