They don’t want to admit they were wrong for fear of backlash from the town
The type of figurative language that is used in the sentence from George Orwell's novel Keep the Aspidistra Flying is a metaphor. A metaphor is a figure of speech that compares two different things in an implied way. In this line, the public is compared to a swine and advertising is compared to the rattling of a stick inside a swill-bucket.
Honestly I'd answer this truthfully if Shakespear didn't make me want to shoot myself.