It's more like "don't come in to use the AC and shade in the store if you're not going to buy anything". I am not making an opinion on the practice, only on your analogy.
IHMO, it would be very reasonable for FB to deny service to ad-block users. But, I understand they'd rather attempt to keep you around first.
Shoppers aren't the mall's customers, businesses are. The mall doesn't care about the customers, they care about luring businesses to locate there and pay rent. And if they have a ton of non-shoppers loitering around, that makes their mall more attractive, not less.