An open-faced sandwich not being a sandwich is a bit like soy milk not being milk, and a bit like a half dozen not being a dozen.
One man's "stubborn jackass" is another's "heroic civil disobedient." Truly, greater words were never spoken.
Actually, they can't quite name it whatever they want, because truth in advertising laws apply to menus. The word sandwich is an unregulated word, so the definition can be pretty much anything the restaurant wants, within reason.
My friend and I once sat down and wrote up a multi-paged manifesto that clearly defined the parameters of what truly makes a sandwich. I have regretted that decision ever since. It has led to days long discussions over my classification scale and my defense on it. My argument that open faced sammys are not actual sandwiches has been widely contested and it's good to know that someone else agrees with me.
Open faced Russian бутерброд ftw!