That works just great. But only when it's your own horse and you have 100% control of it and all decisions related to to equipment, schedual, training program etc.
This is not her Pony, she does not have control over it and the owner, who is afraid of it, also rides it, or tries.
That's a no win set up that is doomed to fail and best and hurt somebody at worst.
And, yes, it was probably fine when she bought it. Because it was soft and out of shape and had a Pony Jock ride or GTJ session right before she tried it. Or the drugs wore off.