It isn't remotely difficult to grasp. As far as I am aware those clauses are inserted for legal reasons to cover the airline in the event of genuine emergencies and so forth. THey are not designed to be a convenient fall back to help with their own administrative and operational needs.
Our contracts with students allow us to remove a student from their course at any time without explanation. It goes without saying we have never done it and never will. Falling back on these clauses in a contract is the act of an utter ****.
And I have now used the term plane about 5 times. Will you please take the ****ing bait!