That's kind of what I was thinking. Thank you. I feel like it's just gonna make him head shy.

Here's someone's video about what I mean: https://youtu.be/rjejpkzusQ4

The problem I'm having with it is my horse does not respond to the wiggle (because he doesn't know what it means) so she was escalating pressure to yanking on his halter and waving at his face. I absolutely hated that - he's a baby, and a very soft one at that. I feel like that will eventually just cause more problems in the long run.

You're right, and I will stand up for him on this. At the end of the day he is my baby and I don't want him trained like that. I really was asking because this is my first young horse and I wanted to check to see if there was a hole in my knowledge before saying anything to her - I'm always willing to hear other perspectives!

He isn't pushy at all. He's only 9 months old but if you stop, he stops. You turn, he turns. He leads like an old man. I can place my hand on his side/hip/shoulder and softly click and he has no issue stepping over. She gets sent a lot of problem horses so I think she's a little too gung-ho on this with my baby who was bred/raised with care, has a good disposition, and doesn't have any "bad" behaviors at this point. He's just not understanding the cue at all and I think he's confused. I do agree with the reasoning of having multiple cues and being able to back from a distance so I think maybe I will try to tackle this one on my own and just tell her we're putting it on hold for now.

She escalates in 3 second increments. She would say "back" and wiggle the lead rope for 3 seconds, then when that wasn't working she would say "back" and yank the halter 3 times, then when that wasn't working she would take her other hand (and the end of the lead rope) and wave it around my horse's head while continuing to yank, say "back", and step toward him. She would stop when he took a step backward but he was mostly just evading to the side so she was following in front of him. I don't think he learned anything from that.

Yeah we're not getting that at all. In fact none of her personal horses have an engaged sensible backup when using that method either, all of them throw their head up and try to evade by turning. Maybe it's not the cue itself I hate but the fact that we aren't getting nice results with the method of training being used to teach the cue.

It might be. She doesn't spout any one particular training method so I'm not entirely sure where it comes from but everyone I've seen use it has been more on the western side.