The Harley rider was wearing protective clothing. If you look at the picture Joe posted, you'll notice his wife wearing full clothing, and see his jacket draped over his windshield.
I tend to believe his story that he looked away for an instant and when he looked up, the cars had stopped. IIRC, the Park Rangers were flagging the stopped car to move along (remember, all memories are mere "flashes and glimpses"). I remember seeing this guy sliding sideways (he must have hit the rear brake first) at about 35-45 degrees to the line of travel. "Oh-my-God! This isn't good." Glancing in the right mirror and seeing Joe headed to the fog line, then thinking, "Whew, that was close!" Then seeing something spinning on the ground to Joe's left (later realizing it was the left pannier) and Joe stopping. "Oh dang, drat, heck and pshaw!"
Thankfully no "body" was injured. It should remind all of us how a mere moment of distraction can have dire consequences (Uhm, don't tell me you never look away or are distracted by scenery, etc.). The Harley rider was very apoplogetic, and severely out numbered. PennerK was a godsend. So calm and collected, matter of fact, etc. He sure kept the focus and attitude headed in a good direction.
Now, heal, Joe. Get the bike repaired and let's ride. BTW, to add my +1, how's Linda? You are both in my thoughts and prayers.