The Captain shoud be ashamed of him/herself.
They have a responsibility to the welfare of all passengers and that includes temperature control and "management" not heating the cabin to 45 degrees. If it was 35 outside with that many pax it would be 45+ inside after 45 minutes.
No external air cond cart? No problems do not board. Try and get approval (prior to boarding) to start one engine on the bay and get the packs going. Not clearance to do that? No problem; do not start boarding.
Not permitted to open the doors after the bridge is removed? then man up use some command decision making and open the doors and have the crew guard them. Not willing to do that, do not board and cancel the flight. Simple
When you pay peanuts and treat you staff like
, they act like monkeys