No she's a servant. OTOH Clergymen are supposed to be gentlemen, and conduct thenselves accordingly.
I understand your point that the customer should have conducted themselves differently, But it doesn’t have any bearing because this is a professional setting for the waiter, not for the clergy. If the positions were reversed, and the clergywoman was rude and disrespectful to someone encountering her in her professional setting, a church service, funeral, etc., then I would fully expect that person to bring both barrels to bear with the church leadership or any overarching entity.
If you have to earn your money doing anything, it is your profession. And you have to do it well (unless we find ourselves, perhaps soon, living in an environment where employers cannot fire employees for poor performance) if you expect to keep it your profession.
I will be clear: I agree completely with you that this customer should not have acted the way she did. I, for one, don’t see how she can be legitimate “clergy” and treat people that way. She probably got it out of a Cracker Jack box. But just as there are good people and bad people, kind people and mean people, generous people and miserly people, the same applies to clergy or any other endeavor in life. The fact that this fat piece of crap “clergy” called Applebees and demanded people be fired simply confirms my assessment. What a turd.
But it is all irrelevant.
Management and ownership of the restaurant determines what behavior is appropriate with customers. If you, an employee, don’t agree with the company line, and won’t get any back up from your management if you are mistreated verbally by a customer, the choice is yours: Do you wish to work in that environment or not, an environment where your manager/proprietor will still back the customer even if they treat you disrespectfully or curse at you like a sailor?
If you wish to work there, you have to adhere to their rules and guidelines, which usually prohibits being disrespectful to customers. If your desire to tell a rude customer overrides your adherence to company guidelines and you decide to tell a customer to stick it where the sun doesn’t shine, that is indeed your choice to make.
Lastly, I read the linked article at the Manchester Guardian, and I couldn’t have less respect for the dumb ass person who got fired. The rule of thumb amongst those who serve is that you can be as rude and derisive of a customer as you want, as long as you keep it behind a firewall with the customer. Sure, she was outside of work when she posted this thing (again, an idiot who thinks the Internet gives her the right to post anything) But you know what? It was no different than a waiter verbally accosting a patron of her eating establishment in Walmart and giving that patron grief.
I work in healthcare, and if I encountered a formerly rude patient at my child’s baseball game and gave it back to them, I wouldn’t have a leg to stand on if they complained to my place of employment. I would fully expect to get fired, because that crosses the firewall between a server and a customer.