As an amused outsider to this thread, let me say we went through this exact same evolution at Delta. Coming out of the BK, they hounded us with the "APU Sheriff" whose job was to track down errand pilots who violated the APU window in the quest of a cool cabin. It took many months, but we finally broke through with the thought process that customer comfort was part of customer satisfaction. It took a concerted effort to write up non operational ground air units and non compliant ground personnel to force the issue. Keep banging the drum. It'll eventually get heard.

Unfortunately, we still have some holdouts.