The guy you ran into, how did he fare in the accident ? As I understand his explanation he felt the rear of his Harley go sideways.
And I'd bet it did as my front wheel broke the triple tree stop bread and my front wheel turned 90 deg. to the direction of travel right before my bike went flipping through the air end over end. At that point I lost track of everything and woke up 30 minutes later. But I do remember the events leading up to the flipping through the air part.
I followed him around a slowing car that was obviously was turning Right at the upcoming intersection. It appeared we were going strait , but just as I was checking my mirror and getting back in my lane Harley guy was braking to do the right hand turn. Why pass somebody then brake 98% hard just to get the turn before the other guy all with-in 5 seconds or less ?

I may never figure it out but to declare it to be an OldFeller Stunt.

Harley guy had a truck turn Left in front of him about 3 years ago and he broad-sided the truck . I bring this up because this same feller is who I was behind. Also there was a truck coming from the other direction and turning left onto the same road as the two bikes and one car was turning onto Truck had the turn signal on. So , if Mr. happy braking guy could have been re-living a past event ? I can't say for sure but it still don't make any sense the way events unfolded and I may never know for sure ?

I'm going for another "Check-up" CT Scan #4 this evening, for 5 week anniversary.