OR, maybe the Harare police were using water canons where the TAR racers were scheduled to be. Same day after all.
I think if a country having unrest was next up, producers might take a day or so to discuss the safety or practicality of the next scheduled leg of the race.
Which kind of raises an interesting question. Have they ever said if they have back up or alternate plans in case of disaster, civil unrest, or other issues? I would think they'd have a back up plan, but don't remember seeing that addressed.