Ghez man, that sucks. . . . On important things (such as this) I always try to get it in writing and over-communicate to the point of redundancy. You might tell the AD you'd really like to settle this with him - man to man -- but, if need be, you will go over his head to the Supt (or, whomever).
Also, the pen is mightier than the sword. You might write up a short report of the 'incident'. Show it to the AD, and let him know that you can send it out to over 100 newspapers in less than 72 hours (via the net) - if he hasn't changed his mind.
How long have you taught/coached in this district? Have others from your school went to this event and NOT got docked for it? It is sad that they are doing this to you. I’d fight it. I have taught for 19 years. I have fought a few battles during that time. Rarely have I lost (I’m not bragging – I’m just saying – if you believe you are truly ‘right’ – fight it, they usually cave.) Don't bluff.
“To go against one’s own conscience is neither safe nor wise.” Martin Luther