I'm a bit confused that it is an 'introduction', but aimed at piano players of grade 6 or above. Maybe more of a conversion course? Or maybe the wording is just to keep the half-term riff-raff out.
What is really needed is something to inspires those who are just starting out with keyboard instruments. Too many seem to lose interest during initial struggles, before finding the world of organs. The earlier they get that initial 'wow', the more likely some will find the vision to go on to become superb musicians. The best organists seem to have come in contact with the organ long before the age of 10. One would presume (Mozart apart) thet they were not grade 6 at that stage ....
Occasional tending of saplings is good, but someone needs to plant a few acorns once in a while.