This is a nice example of a not so common fallacy, the "fallacy fallacy": suppose that you have an argument a for the proposition p:
a -> p
It does not follow that:
~a -> ~p
Which is to say, showing some cherry-picked argument for Facebook being unethical to be invalid tells us nothing about Facebook being unethical or not.
Given that you crated a throwaway account one hour ago just to post this comment, I suspect that you are aware of what I am saying, but others may not be.
For those interested in a less cherry-picked source of claims against Facebook, there's even a Wikipedia page just for that (warning: it is quite long):