They are giving poor people another choice they can have access to a very limited Internet or they can have access to none. If they would just loose lot's of money by giving people this choice it wouldn't be a reliable business and soon it would end. What's so bad about giving people another choice? No one is forcing them.. and it's way better than doing nothing.
I'd be OK with something more subtle, like a mandatory FB account (kind of like how Google does with G+ and their other services). But limiting what they can see on the internet...I wouldn't go so far as to call it unethical, but certainly deplorable. Especially for a company with as much capital as FB. They don't need to sink this low.
