If the business has a problem with the way he dresses, it should communicate that to him through channels. Not humiliate him in front of a client.
When you have a young apprentice, fresh out of training, full of
shit the confidence that only comes from having been to the best training provider money can buy and being right up on the absolute best and latest practices and methods, and just oh so much better than the old hats, then a bit of public humiliation can be the best thing for you. And in many cases, for the sake of the team/company, it's that or the DOLE queue.
Have been there myself. Freshly trained and knew so much more than those who had been doing it for years. Also got a couple of "fun" (but minor, no scars) electrical burns because I did a job in the "safety-standard" way, not the way my experienced boss insisted I do it. Sometimes you can't tell people, you have to let them suffer embarrassment.
In today's world the little lass would be off crying to their lawyers seeking millions in compensation for their humiliation and life-long psychological scars. Back then we took it in our stride, if necessary went home and changed pants/other clothing items, and thought about how we could do a revenge prank on others.. My best I think was a brake-line clamp on his fuel line when his wife rang about some serious emergency (she was in on it of course!), and the poor bugger spent a few hours trying to work out what was wrong on the side of the road on a wet afternoon with the knowledge his wife had threatened "true wifely nastiness" if he wasn't home soon... That or the snap,crackle&smoke generator fitted inside someone's very expensive just-paid-off-last-payday rear projection TV.. No damage to the unit, but the owner's pants didn't fare so well..