In using a non-MBTI instrument, PT can basically sell their own Jungian typing services while still using the same MBTI type codes that everyone in the typology community is already familar with. They get the best of both worlds: name brand recognition of the MBTI type codes and, freedom from the ethical limitations set forth by the MBTI's publisher. In other words PT can get away with typing people completely by PT's own arbitrary interpretation of how their clients are supposed to match up to their concept of the 8 functions regardless of how the client scores on the Majors PTI instrument they use. If PT were using MBTI however, the practitioners would not be allowed to type clients as types that deviate too far from the test results. Of course PT (Peter and Danielle, really) pays lots of lip service to the MBTI in their videos. Wouldn't want to bite the hand that feeds you!