If you can't burn/ban the book, punish the reader to achieve the same result...
True enough, but while some groups, (in this case in England) supporting Sharia and jihad are pretty well defined, they are trying to ban "Right Wing" websites as well. That gets a lot more vague when it comes to who considers what to be 'too radically' "Right Wing".
Considering in the US the SPLC had defined some mainstream conservative groups as Far Right Hate Groups, it becomes a matter of perspective, and not a well defined ideological limit. The very vagueness and subjective nature of what constitutes a "Right Wing" site and the attempt to find moral equivalency between that and a site promoting violent jihad is a stunning piece of Liberal overreach.