I fox hunted many years on an OTTB that pulled like a freight train. The double twisted wire kept me behind the field master. And I agree that in a perfect world, properly schooled, a plain snaffle or pelham should have sufficed, but my horse was fast, forward and loved his hunting-no number of pull ups or downward transitions was going to trump the hounds. The proper bit is one that suits the horse and the job he’s doing. Maybe a horseman to horseman chat with the trainer could ease your mind.
I think that if the horse’s care is your responsibility you are right to ask the question, just don’t pre-judge 'til all the facts are in.