Very simple: if you want to be treated like you’re using a legitimate vehicle, behave like you are; if you want to be treated like a cyclist, behave like one; if you want to be treated like an arrogant yob…
Just because something isn’t specifically banned, it doesn’t mean it is specifically allowed. Try walking through the same park with a chainsaw running in your hand, then when you get stopped for carrying an offensive weapon, ask where it mentions chainsaws.
I am sick to death of the various sports and activities that I take part in getting a bad name and provoking hostility because of the actions of an irresponsible few who think that the law doesn’t apply to them, and if it does, it is nothing more than a series of technical arguments to be won or lost.
It’s all about courtesy and a sense of responsibility. As a motorist and motorcyclist, I have been stopped by the police a few times. I have found that being polite, listening to their point of view and putting my own view calmly but courteously usually does the job - unless of course I have been obviously breaking the law. Even then, I have escaped with a polite warning - once for speeding in the car, once for a faulty rear light on the motorbike, once for cutting across a pavement on the bicycle.
The law may not mention unicycles anywhere. It does mention things such as committing a breach of the peace, endangering other road users, failure to stop at traffic signals and so on. In many jurisdictions, it is an offence not to stop when instructed to do so by a police officer.
Chances are, the cop had never seen a unicycle being ridden before, other than in a performance context. To the uninitiated, it looks dangerous. It looks like it may endanger pedestrians or other road users.
However, if you are wearing the kit, riding safely, giving clear hand signals, and if you stop, listen, explain, and if necessary defer, there is one cop who goes back to the police station with a better view of unicyclists, and a funny story to tell his or her colleagues.
Fight with a cop and, because they are human, they will fight back with everything they have at their disposal. Push someone and they will push you back.
Personally, I don’t think that pleading that it is difficult to stop is a convincing argument that what I am doing is safe.