At 300 hours Fred barely knows how to fly themsleves.
They are not even remotely qualified to make a judgement about if johns habits are bad, good or standard. An FIE is in the position to to do this which is why john really doesn't give a
what fred thinks. And even if they are bad habits there is absolutely nothing Fred can do to stop John from flying or Instructing.
The mostly likely event which will occur flying with john is that Fred will do all the learning and John will have an empty pocket for a tick in the box.