I don't think UKIP 'pulled the strings of the law', I've read a lot of people say that they had visits from the police because someone (who was not famous or important) complained that they were acting in a socially inappropriate but probably not illegal manner (for example). To pull the strings of the law they'd need to exert some special influence that was not available to the ordinary person, but that is not the case here.

Raising your fist clearly implies you are going to hit me if I don't agree. Here the police made it clear there was no crime committed and took no action when he said he wouldn't take it down.