I agree that governments have an appalling record of sneaking in what turns out to be permanent legislation by the back door; also for using legislation for spurious purposes for which it was plainly never intended.
But there are in the case of the Olympics conflicting issues. The actual event itself is a forum for the world's ultimate athelets to compete, and a chance for lesser mortals to watch. That fundamentally is it. Most of these athletes devote their lives to excellence in their chosen event. If the athletes want to go and compete, and I, or anyone, wants to go and watch, why should I or they be impeded, or have the day ruined, by protesters who have no issue with the Olympics per se, no issue with me, and no issue with the athletes, but issues with government policy?
Of course, the reason such events are chosen is because of the media attention any disruption would attract. But the problem to me is that in some cases (depending on the nature, venue and likely course of a 'protest') it is dangerously close to becoming more akin to blackmail: "change your policies on X, otherwise we will ruin your Y".
The second issue is that the bigger the protest, the greater the likelihood of it, or parts of it, being commandeered by criminal elements, who take advantage of the stretching of police resources and the weight of numbers to engage in pure criminality.
I entirely support the democratic right to peaceful protest, but if a protest goes far beyond being a passive event, and is additionally an active event which does not only protest, but chooses a method an/or a place of protesting that goes further, and also seriously impinges on the rights of others to a very significant degree, should be susceptible to some form of control.
There cannot be a universal right to do whatever you want, wherever you want to do it, as long as you're carrying a protest banner.