You're misrepresenting what Uberpod has said.Dude, you're pissed that a waitress doesn't remember you're an atheist. Clearly that is you.
He didn't suggest that a server should memorize every customer's religious preferences. What he did suggest that "have a blessed day" should be reserved for situations where the server knows it's welcome. It could well be that the restaurant's so busy that the server doesn't know the customer' s preference most of the time... in those cases, exactly what's wrong with saying something neutral?