Waiter decides that he is my girlfriends white knight

I went to a restaurant with my foreign-born girlfriend. She asked me to order for her because she is not very confident in her English in public. Even though we communicate very well I indulge her as she wishes. So we peruse the menu she tells me what she wants and when the waiter comes over I inform him. So so this moron says "perhaps the lady would like to order for herself". And I am like you asshole mind your own business. It was very embarrassing for both of us. I just can't get over why he thought he needed to do that. His tip was MYOB.

Edit: my bad for not making it clear that I did not verbalize the negative thoughts about the waiter. They were only in my head. When my girlfriend looked up at him obviously hurt and said "my English" in her very weak voice . He just left the table and got our order. I was then and still am furious with the man for ruining our evening and making her feel bad. I did nothing other than not give the man a tip which he did not deserve. If you are going to help a person who was being abused you should have some evidence of that.