I think Kevin's PCS progress is in spite of Joanne. He worked with Shae-Lynn and must have followed her pointers.
I would not compare the Kevin coaching situation with Sandhu or Mira . Mira's mother interfered with things and Sandhu never had the right attitude ( work ethic etc ) Kevin does not have those problems.
However Joanne has taught kevin an absolutely awful axel technique ( which can be seen in her other students as well ) . Even if he lands his quads the axel will always be a problem with the horrible technique he has on that jump.