Oh come off it. She looks like a chav. Don't forget they are going out for dinner. Most people wouldn't want to sit in a restaurant with a woman in their underwear. I wouldn't. Even beach restaurants have a minimum dress code!
It doesn't matter that she has a good body. It's not the point. You may as well say it's acceptable for her to go naked because she looks good naked.
It's utterly utterly classless.