Agreed - on both of your above statements to Rob and I. As to the horse or the horseman: As I have screamed before, the question is moot and has little bearing on the big picture of the assassination. Its biggest impact may have been to give Dr. Mudd more publicity than he ever thought he would get when he met Booth and then introduced him to Southern Maryland agents.
Agree, that since the broken leg occured after the deed was done
you can make the case that where it occurred has little bearing on what happened. However, it was the broken leg that eventually led to his death and I'm certain forced him to change his route. I just find it intriguing when an unexpected event changes history.