What, no loud pipes didn't save them jokes? Does a loud pipe save you from someone else with a loud pipe? (Yeah yeah not all Harleys have loud pipes.)
Since we're all just speculating here, my guess is that all three Hardleys (including the one parked on the side) were all riding together. First guy slows and then goes through, third guy thinks they are doing it road captain style so he's just going to ride through without stopping and accelerates to catch up with the first guy, just as the second guy follows rules of the road and stops.
Third guy then rear ends second guy since he knows not to use the front brake. Of course if both bikes were smashed in the front, that shoots this theory all to hell.
Advanced pancreatic cancer found 04/2010. Have outlived +/- 97% of patients with this diagnosis, but 08/2013 cancer now in liver, vascular system and lungs with 20+ lung tumors. Sick/weak sometimes, not riding much. No more treatments & now under Hospice care.