Not that I agree with the knee-jerk reaction put forward by Cameron, but actually, protesters will protest. There's a big difference between rioting and protesting, and it's important to make that clear.
By horse-charging and kettling peaceful protestors, the UK police have been doing their best to blur the distinction, trying to meet every protest as if it were a riot, and perhaps turn it into one.
That's a sweeping generalisation. I participated in the big march against cuts and the police were very respectful and only moved to contain those who were participating in violent behaviour (trashing shops, etc.). The vast majority of protesters were peaceful, treated well, and not kettled or horse-charged - a direct response to the previous condemnation of those sorts of tactics used against the students in the previous marches.
I know what they are, but I don't think that any such thing justifies the sweeping generalisation the previous commenter made. The police have been employing a range of tactics, and some have worked better (in terms of public opinion too) than others. Kettling, as far as I have seen since the public outcry over its use in the student situation, has not been used against peaceful protesters since.
Taken out of context (as you did) it isn't controversial.
But in the context of the article linked to it implies that it is a problem that the government needs to do something about by restricting the said free flow of information.
I didn't take the quote out of context any more than you did in the grandparent!
I definitely have a problem with the Government restricting the flow of that information; but that doesn't mean that the flow itself isn't problematic at times.