I'm not sure why it's silly. Brad admits that it's a tricked up example, and it is so for a reason: it points out the implausibility of the whole Marxian "exploitation" line. Namely:
"Thus the labor theory of value category of "exploitation" does not map onto what either ordinary language or our moral intuitions call "exploitation." There are social and economic changes that are good that are, in Marx's schema, increases in the rate of exploitation. There are social and economic changes that are bad that are, in Marx's schema, increases in the rate of exploitation. It's simply not a useful tool for either moral philosophy or political action."
The vision of exploitation may be Dickensian, but who do we think we're talking to? Do we think that people would respond to the kinds of arguments that Liza makes about women working for Wal-Mart if instead she were talking about players in the NBA, who are, in the Marxian idiom, also exploited and whose working conditions also stink in many ways? Are we less compelled because the rate of surplus value extraction is less in the NBA--(if it is)? Or are we not all Dickensians now?
Christian