If you'd want to stay true to the core of the story, that the actors are being arrested, because they apparantly "beg" people for money, then I don't really have a good idea on how to spin the story.
But if you just want to come up with some good arguments for why a vigilante like Batman should be arrested by the police, then that's another story. After all, we are talking about an armed lunatic that operates outside the law, and who does not recognize the long established fact that the law accord citicens with a number of civil rights, including protection from assault, threat and intimidation, violence, abduction, right to legal representation etc. Additionally, this caped maniac is known to carry any number of unlicensed types of equipment, lots of it either potentially lethal or suspected to enable the user to invade the privacy of private citicens! Furthermore, even if believe that this masked vigilante only assaults those individuals that break the law, and want to equate him to a regular law enforcement, then you have to own up to the fact that this "Batman" is operating without a licence, and does so for free. The fact that he operates without charging anything for the service, is simply an unfair businesspractice, which in the long run will lead to a monopoly situation within the law enforcement area, since decent companies like Lone Star and Knights Errants can not operate for free. Forcing these companies to compete with an entity that charges nothing for his services, which clearly overlaps their area of operation, is clearly a breach of several counts of ethical business practices, and unlawful. Finally, the masked menace is infringing on the territory legally assigned to a law enforcent agency, which has won the right to patrol the area through the long well established practice of bidding for the project.
No matter how wellmeaning this carnival clown might be, an orderly society simply can not accept or survive in the long run, if people elect to blatantly flaunt and ignore the law, simply because they believe they can do a better job at something, or because they don't agree with the law on a particular issue. If we allow one such misguided individual to roam the streets at will, flauting the law, it furthermore sets a very unfortunate legal precident, which will ultimately lead to the complete breakdown of the orderly society, reducing the world to a state of complete anarchy where there are no laws.