The panic clip reduces risk greatly. Perhaps you could ask the guy to get them, if he doesn't already use them. You could even send him an anonymous note suggesting it, if you're more comfortable with that.
I think lots of racing stables do this. I recently read an article about a horse here in New Zealand that was killed doing this. They were training horses along a beach early in the morning and someone walking saw one horse fall and get dragged for over a kilometre. Their excuse was that it was dark and the wrong horse was put on, the horse was only 2 and had never experienced it before.
That just makes my stomach sick. I don't understand how someone could do this to a helpless animal. Its disgusting and if people can't take the time to do this properly then they shouldn't be in the care of ANY type of animal.