It's a lot easier to curtail things like this on the internet. It would be dirt easy to set it up to only allow certain content (let's call it "constructive" content, like Wikipedia, various news sources, etc.), while blocking content with specific keywords. Prisons have a finite amount of traffic, it's not like we're setting up the GFC. It's dirt simple and dirt cheap to set iptables up to handle this with the limited traffic coming out of a single prison. I could probably do it for less than $400 on some budget hardware, and have it be pretty solid/reliable. We should be allowing these people access to the information and knowledge so they can better themselves and broaden their horizons. We can do that while simultaneously blocking their ability to "contribute" to the global discussion if we need/want to.