Whether he responds better from the ground or not, you always have more control of where your horse is moving from the ground. That situation could have been an entirely different post today. He was so distracted by the scary non threatening monster, he didnt see himself throwing the both of you towards the scariest, deadliest monster. That must have been terrifying for both of you and I'm glad everything turned out the way it did.
Try what Cherie has suggested. You could also try doing that ride early morning or late night when traffic is less busy.