The BBC started its report this way: "Rush Limbaugh is arrested..." then described the actual process which clearly shows he was not!
How Clintonesque do you want this to be ?
Was he charged with a crime ?
Did he turn himself in ?
Was he booked ?
Was he then subsequently released ?
Unless you are under the impression that at any point, such as when fingerprints and photos were taken he could have simply walked out - he WAS under arrest.