I would either circle him or pull back with my reins but sit hard too. Does that make since? Sarah was annoyed that he sat deep and pulled back and said "He was ripping on the horses mouth" I found that a bit over dramatic.....She is REALLY big into natural horsemanship, Pat Parelli.
The horse reared up when the guy asked the horse to stop jigging the horse also bucked a series of times of times, the guy immediatly started circling when she went up into the rear...What would you do??