My initial reaction is that this escalated completely in the wrong way. If you never drove in St. Louis then you need to. I can't understand why these researchers chose to do this on what I would consider a very busy public highway.
Security research is supposed to be done in a safe and ethical manner. I am glad nobody was hurt but this is a really dangerous way to prove a point. For the driver and the other cars around the driver. I'm afraid this might make things worse researchers. Not better. Be safe out there folks and think before you demonstrate.