Only the FAA can request a reexamination (709) of an airman usually as a result of an accident or incident where his competency was in question. If someone is having difficulty during training perhaps the organization needs to look within itself first.
APDs, DPEs, etc. act as the FAA in the 121 flight training world. It's not out of the realm to have them issue a 709 ride. In the case of PDT, I'd have to believe it isn't justified. My guess is it's way over the top for what would essentially be a non event. I don't know for sure because I'm not there and I'm not I. The know. Just my assumptions after having been through training with them, and my treatment in sims.
PDT training is not for the faint of heart or those with easily hurt feelings.