There's also a valid reason to think the guy was "underdressed". I've seen many saggy pants wearers who are engaging in indecent exposure. Many.
It's not a stretch to think that one of these made it onto the plane and a private company has a right to speak up about it if it is offensive which it appears this might have been.
Given the contents of this article, perhaps you should have worded that differently. Yes, I know, different spellings, but I read it wrong at first due to contextual confusion. :)