The serious point is that there aren’t very many working-class voices in fiction, and when the working class are addressed in fiction, then there will generally be one of two modes that will be used: you will either have the working class deplored for their vulgarity, for their poor decision making, for their horrible abject lives, for their stupidity, or, often more sympathetically, you will have the working class pitied for the terrible things that have been done to them and the way in which they have been made to live.
This is simply wrong. Working-class voices are very present in fiction, and they are not treated as stereotypes. I don’t know what he’s reading, but he’s missing out on a lot. To cite just one author who faithfully depicts the working class, read Richard Russo, notably his wonderful Nobody’s Fool (Amazon.com, Amazon UK) and its excellent recent sequel, Everybody’s Fool (Amazon.com, Amazon UK).
I’ve read the first chapter of Moore’s Jerusalem, and I plan to read the rest when I have time. It’s a huge book, very Joycean, and requires a great deal of attention. But he does seem like a very interesting writer. (I’m not a fan of his comics.)