Remember that there are two reasons for this proposal :
1) To look like they are doing something. In particular responding to those well known experts in the field - aka victims and relatives of victims who believe that having been on the receiving end makes them an expert on the subject. By that logic, "I was once bitten by a dog" equates to "I am now an expert on animal behaviour"
2) To get a situation where the default is to have a "filter".
Once the filter is in place, and everyone* thinks it's a good idea, then it can slowly be increased in scope. Anything that anyone can convince the leadership of the day is "bad" can then be added later. Think of the situation in the USA where in some places it's not allowed to teach evolution as the bible bashers are adamant that only creationism can be "correct".
Every tabloid and pressure group will have a view on why their pet hate is bad and must be banned "for the sake of the children".
Politicians too will soon find things that "must be banned". Sooner or later the Quran and Tchaikovsky's 1812 Overture will be added. Wonders how long it will take for people to work that reference out
Nigel Whitfield puts things quite well in a blog post.
* Well everyone that matters, clearly if you aren't for it, then you must be a kiddy fiddling, animal bothering, terrorist such is the way the emotions are deliberately manipulated.