The billboards are written in context to anti-alien sentiment caused by the Rikti invasion, and are therefore fine as they are. As stated, the billboards tie into the story and are not "amazingly out of date and out of sync with the game as it is now". Also as stated, Paragon City is in a fictional United States so there should be nothing "jarring" about seeing an American flag on a billboard. Now, stop being overly sensitive and looking for things to be offended about.