Originally Posted by JohnMacWW

I think that ignoring an "official" whether they are airport-based contractors/employees or airline-based contractors/employees, is something you should do carefully. If you get away with it ( walking by them muttering Icelandic) fine, but if they say something very clear that is an order like
"Sir, stop where you are and come back here and size your bag" and you ignore that, you are taking a good risk of having a bad travel day. If that person is angry/difficult/ annoying enough, they might drag someelse into it that has clear authority. And that person is very likely to side with the contractor/ employee at least on the point that you should have obeyed their orders.