What really should come to mind is just an explanation, a clarification or whatever in an ethical way. I had no knowledge before hand that there was already one concerned member who had raised this similar query I had had.
What bothered me more was my position as a school principal had been mentioned. belittled. They questioned my authority, my intrusion of such business which called for the personal decision of every teacher to buy the t-shirt or not. It was no longer my business so to speak according to the commentors.
Should a teacher react that way?