Seems to me that you are attempting to apply your definitions onto someone else. Namely, you are trying to tell United what their definition of “overbooked” should be. They are a private company, regulated by the DOT. Those are the only two entities that get to define “overbooked”.
That is such a convoluted thinking I can only assume that you are making a joke for which I thank for you for. I always appreciate a Good bit of jocularity that brightens my day.