The airline is not a government agency. They can refuse service to anybody they wish. So long as they refund the cost of the ticket, I don't see how this is a problem. Businesses are allowed to enforce a dress code (everything from "formal tie and jacket" to "no shirt, no shoes, no service").
It's similar how they would probably object if you went to a Chuck'e'Cheese dressed 'too provactively'. Also, clothes don't tell the whole stories. Posture can have a lot to do with it. An outfit that doesn't look too smexy in a still image will look a lot different if the person wearing it is (consciously or unconsciously) flaunting themselves.
-----------------
Epsilon
It's similar how they would probably object if you went to a Chuck'e'Cheese dressed 'too provactively'. Also, clothes don't tell the whole stories. Posture can have a lot to do with it. An outfit that doesn't look too smexy in a still image will look a lot different if the person wearing it is (consciously or unconsciously) flaunting themselves.
-----------------
Epsilon