I believe that with nearly any ISP you're contractually prohibited from sharing your home internet connection with neighbors or anyone outside of your residence, so creating a service explicitly designed to do this is a bit of a grey area.
This is called 'disruption'.
What about having bitcoin payment for x minutes of access to the hotspot? :)
I'm sure they could cut me off if they didn't like what I was doing, but they could cut me off at-will so it's not worth trying to read their mind.