The great thing about this story is that everybody's "right."
The woman has the right to require her patrons to dress in a certain way.
You and your brother-in-law-to-be have the right to not patronize her business.
Ain't this a great country? That's free enterprise for you. I luvs me some capitalism.
Now of course, that woman was a massive-word-I-can't-say-here-because-I'm-a-fine-upstanding-moderator-who-always-upholds-the-AUP, but I think you can guess the word I have in mind.
And you probably didn't have to "make a point." Everyone makes choices and everyone pays the consequences...