Why so disappoint?

I remember about a year before I left my restaurant job, I had a customer literately come in 20 minutes before closing and begged us to let him sit down to eat quickly. A server comes into the kitchen and asks if I would make him ____ and he would be eternally grateful. We had already started shutting down for the night, but I made an exception.

So, I had my cooks continue to break down the kitchen for clean up as I made his medium-rare steak with salsa verde, which was accompanied by sauteed potatoes, carrots and parsnips. I plated and put the dish up in the window. Then went to go help out my staff with the clean up and start inventory. Suddenly a server asks if I had a moment. "Oh boy" I thought, I hope there wasn't any issue with the food. I walked out onto the floor and said hello, as he greeted me back and continued to look past me into the kitchen. I stood there for a moment, then asked if there was something I could help him with. The customer replied, "Yes, I'm waiting on the Chef so I can thank him for this lovely meal." I stood there in front of him with my black chef's coat. It had the restaurants name, my name and title of Executive Chef beneath it. I smiled and said, "Yes, that would be me." Well, his face changed as if someone was playing some sort of prank on him and he looked me up and down quickly. Instead of apologizing he says, "I thought you were a guy, since only men can cook steaks that good. You did a great job by the way, the wife will be so surprised when she finds out your a woman. Maybe you can come teach the wife a few things." I was visibly annoyed as he stood up and pat me shoulder like some 4 year old kid. The server who had quietly watched from the edge of the kitchen (its open concept), quickly walked over and snatched the tip up from the table. He walked right over to the customer who was just about to leave and held the door open for him. Just as he stepped out, Zach says to the customer, "You forgot this, goodbye." Then placed the tip back in the mans hand and closed the door.
I just shook my head and Zach came over to me. "I cannot believe that guy, I'm so sorry about that." I told Zach it was okay and that he should have kept the tip. But, he refused and said he'd never take money from some rude asshole. I tried to smile, feeling somewhat bothered by the customers reaction. I think at that point, I was so numb to stuff like that.

Well Karma would so have it that he came in to make reservations two nights later and my servers remembered him. Guess who was on the permaban list.