If, through inclement weather (in case of any outdoor show) or other happening not within the control of the club, a postponement becomes necessary, the commission may grant an extension of the contracts and set a new date, and the action of the commission if a show called off shall be binding upon all parties to the contracts. A small advance sale shall not be regarded as legitimate reason for a postponement. Indoor boxing shows shall not be canceled for any reason except with the written approval of the commission.