I find this quite hard to get my head around:
You are AGAINST the police taking the electoral roll, etc and going door to door to see if it's still current (and no doubt taking the opportunity to ask if residents have noticed anything odd recently in neighbouring properties), with a view to identifying any premises where an intelligence-led (the oddness/inconsistency reported from this process being the intelligence) surveillance operation may be merited. Total invasion of privacy: knock on door, quick chat on doorstep and confirming what the cops know already fro publically accessible sources (or what you will shortly be making known anyway one way or another if you've just moved in).
But you would SUPPORT the police preventing people going about their lawful business because they've blocked a particular road or searching through their pockets as they go about that business or putting them through a search arch when all that they have done is gone to work / pub / get a pint of milk. Maybe repeatedly, day after day until the conference is over.
Surely those latter steps are far more invasive than the first? (I'm not saying they could not be used by the way - they probably will be to some extent - it's the inconsistency in approach I have difficulty getting my head around)