Don't know about BN, but I noticed recently that their Canadian version called Chapters now have substantially fewer chairs than they did a year ago. In smaller stores chairs are gone completely. There's also virtually no wall space to lean against, and they generally discourage from sitting on the floor.
> If you let customers chill for a few hours, they're going to buy stuff.
Let's say you sit for 4 hours and buy two cups of coffee. If the shop is packed, your chair could instead serve 5-6 lunch customers in a matter of just two hours, each spending considerably more than you. On the other hand if the shop is half-empty, it's nice to have people sitting around, because it creates crowd.
So if you add 1 and 1, you will arrive at the exact policy described in the article - no idlers during the lunch hours.