Imagine being an adult and blaming someone else for your decisions.
You can work at a business and help your customers make good decisions, not just the decisions that make you the most money. I have a mechanic I go to who will tell me if something needs to be done or could wait, because he’s so honest he’s always got a ton of customers… so he doesn’t need to rip anyone off.
ETA: He’s also so popular amongst his customers that he spends nothing on advertising, all his customers are referrals from existing happy customers.
The warranty probably only cost a few hundred for the dealership, if they quickly agreed then they were still making money on the deal.