That definitely sounds the best way to deal with the issue. There's no problem questioning authority - that's part of what democracy etc. is all about, but there's a way to do it. I would alway say that if you get told to stop and go away by a figure of authority, do what they ask and then write, email, or phone their bosses, and complain/ask advice on the situation. Police in particular are always very aware of public perception, and depending on the circumstances, if they see someone doing something potentially dangerous, the instinct is to play it safe and tell that person to stop - it's largely because, if they're seen walking by and not doing anything and then the person has an accident or injures someone else, there's Hell to pay in the papers. Most coppers need cast-iron underpants to keep their backside properly covered, because right or wrong that's what a lot of it's about. If they are given guidance from above that bocking within this and that situation is allowed, then if everything goes to pot they can shift the blame upwards.