The branch manager is not saying a word until Best Buy legal goes through all of it. Best Buy has two issues; 1. If the employee refused to sell the laptop, he broke the law. 2. The employee can try to claim a hostile work environment and hunt for a payout. He's not going to have a claim since calling him "sir" is not offensive, regardless of his opinion toward it.
This is going to cost Best Buy which means they'll roll the costs onto customers.
That only applies to employees and management. Customers can't be sued on hostile work environment grounds.
-PJ