Exactly. All you should say to a customer is, “Thank you. Here’s your food. Have a nice day.”
True. The worker was extremely unwise to have that "debate" while at work.
Unfoertunately, if the worker had exactly the same "debate" with the Muslim fellow at his own house, on his own time, the video would probably still get him fired if TacoBell heard about it. Companies fire employees for their private behavior all the time, especially if it's politically incorrect and causes embarrassment to the company.
At 1:00am? I suspect the “customer” was just hanging out wasting time and engaging the employees in conversation while they clean up. Must not have been very busy as he was parked in the drive thru for 25 minutes.