Sure, they can make/break their own rules. It's been a while since I've looked at this in detail, but my understanding is the "Like" aspect of it is optional. On that page:

>After checking in, people will be asked if they also want to like your Page so you can continue to connect with them on Facebook.

Of course, if using Facebook WiFi, you do check-in to the location which triggers a host of other "features" within your Facebook account and experience. Similar to if you check-in to a location with the standard Facebook App.

I can see the argument that it's an extension of that experience, while providing WiFi service in exchange for it.