This seems feigned indignation. Would anyone expect Pinterest to take legal responsibility for what a user posts? This is the standard of posting content to the Internet, Facebook, Youtube, Reddit, etc., and Hubski.
What's more, Pinterest places all blame and potential legal fees on its users.
Could it be any other way? There is no a priori vetting process of content made by the service, so the service must ask that you either don't post copyrighted content, or take responsibility if you do. Of course, even so, someone could still file a complaint against Pinterest. It's not like their TOS absolves them of any possible infringement case.
This article ignores the rest of the content-sharing services on the web.
Kirsten turned to federal copyright laws and found a section on fair use. Copyrighted work can only be used without permission when someone is criticizing it, commenting on it, reporting on it, teaching about it, or conducting research.
Well, I suppose that's the good news. Everything posted here is for the purpose of criticizing, commenting, and reporting. :)