Just adding my $.02. Whether it's right or not for restaurants to stop seating people before their posted closing time, I would never arrive at a restaurant and expect to get served less than 15 minutes before their closing time. I've been in too many restaurants around closing time and have seen the staff cleaning up, chef getting ready to leave, etc. I feel like I would not get the best service or food if the wait and kitchen staff were annoyed at me and wanting to get out of there for the evening. Again, not saying it's right of anyone to be rude or inappropriate, but it's just a courtesy I give to the restaurant.
ETA: For those who don't have context, this thread was moved by moderators from the Midwest board.