Oops I did it again!

Mr. and Mrs. Wellington and their dog "Rebel" were in week seven of our 12 week Family Dog Program. "Rebel" is a 9 month old Lab/Shepherd mix, rambunctious, excitable, but exceptionally trainable and very food motivated. He was a quick learner and was very reliable on the basics, sits, downs, recalls, and was coming along with his loose leash walking. He really was quite typical for a dog his age. The Wellingtons are a middle-aged couple, likely empty nesters, and seemed very committed to his training and wanted him to do well. That's why I was shocked when they showed up in class on week 7 with Rebel wearing a choke chain. To make matters worse, the choke chain was about 3 sizes too big to boot.

The conversation went like this:

Me: "Um, what's going on here?"
Mr. Wellington (looking bewildered): "With what?"
(I looked over at Mrs. Wellington who looked like a deer caught in the headlights.)
Me: "Why is Rebel wearing a choke chain.... which is way too big, by the way?"
Mrs. Wellington: "It's the only way we can control him.
Mr. Wellington: "He does much better when we have it on."
Me: "Well, yes, sure, it's amazing how a dog will respond when he feels pain."
Mr. Wellington: "It hurts?"
Me: "Uh, yes it hurts. That's the whole point."
(Now Mr. Wellington looked like a deer caught in the headlights.)
Me: "He was doing very well in class. Granted he's a challenge, but he was coming along."
Mrs. Wellington: "He's just so hyper."
Me: "Take it off, let's try it again without, please."

They agreed, took it off, and went through the rest of the class as usual. Rebel did fine, like usual. I made sure to encourage them and gave them kudos for working well with him. That was 2 weeks ago and I haven't seen them since. I figure I either made them feel guilty when I told them the choke chain was painful and they don't want to face me again, or they aren't willing to give up the "control" they feel the choke chain gives them. Either way, I've lost them. They will likely resume training at a place that welcomes and/or encourages aversive training methods. Poor Rebel. Fortunately this doesn't happen a lot, but it will always bother me when it does.