Offering the wolves excuses and lies will only make them view you as being weak or uncooperative, reinforcing their Org-given perception that they dictate how your life is managed.
Quietly say to the "School Overseer" that you don't want to be given any more platform assignments for the time being. When he asks why not, just say your reasons are private & personal, and that you things to deal with - but thanks for asking and if things change, you'll let him know.
If confronted within weeks or months, simply repeat, "There's nothing I can discuss at the moment, but if things change, I'll come and talk to you."
They'll get the message!!