But they really didn't block anything. Even the police are saying that they really didn't even disrupt the flow of traffic. If they stopped, blocking all lanes of 465, I would agree with you. But they were traveling at the minimum legal speed (heck, I've seen bluehairs do worse), allowing traffic to merge and exit without any problems, and leaving open the left 2 or 3 lanes for traffic to flow unimpeded.
From the thousands of miles I've driven on interstates, I'd actually be thankful if they'd leave a lane open for normal traffic, instead of drag racing each other at 65 vs. 66 mph and holding up traffic for miles on 2 lane interstates like they usually do.