I was thinking about how dangerous it was while I was reading it too, but I came away far less concerned than you I guess. The deceleration on the highway was the most worrisome, but it's not even in the ballpark of common driving hazards like distracted folks on cellphones or flying debris. A crash from such a thing is unlikely and the inconvenience is pretty minimal.
Even you, the busybody who called the cops because you read an article, said "What was the plan if the trucker approaching at 70mph hadn't seen the Jeep stalled early..." which implies that the trucker would have been following too closely or not paying attention (or both).
It's worth pointing out that the driver was aware of the situation and they didn't do anything dramatic like lock the brakes or throw the car in reverse. They chose a gentle deceleration in a stretch of road that had no shoulder to make it feel dangerous, but, on the spectrum of hazards that most drivers face every time they take the car out of the garage, this is pretty tame.
The fact is, had something happened, it wouldn't have been the disabled car that was at fault.
I think the researchers are in the clear, and for you to have read the article and been bothered enough to call the cops (and post the number for, presumably, the convenience of other hyper-sensitive folk who might otherwise just go back to staring at the neighbor kids from their bedroom window with their phones in their hands and 911 on their speed dial) is nuts.