Civility is not about right and wrong. It's about behavior that few, if any, would find offensive. Bras v no bras is not likely to offend many, if any. Clothed v unclothed will offend many, not all.
You mean, people should be offended by a human body that is not ostensibly naked, just naked and getting some solar radiation, on a boat on anchor, or sailing, where you only get close if you want to and not need to?