I think you'll find that they're on the side of not getting involved in arguments. The official position is that there is no policy against (or for) saving seats and they will not referee.
Really?
So what is the point of asking people for an extra $10 for priority boarding? It was explained to me that those paying the extra fee got their assigned number after "A List" club, or whatever it is they call their frequent flier club.
So they won't referee, but if someone , say with a large group (Sports teams, cheerleaders, etc.) they could theoretically save seats for a crowd.
Maybe you could just offer the money to the person at the front of the line and ask for a specific seat(s) to be saved?