toon
The trouble is when people get on a/c they suddenly turn into closet aviation experts and question every decision.
This is completely out of order.
The question is a completely reasonable one.
If anything, it implies a lack of communication from the crew to explain why the pax were being inconvenienced (aka roasted.)
Mutt's comment about a ground unit is spot on too - I've spent time in Vegas and it's bl@@dy hot in August.