/lit/ - Literature

Can't believe no one has posted Peter Singer yet.

/lit/, how do you respond to someone who claims that the values of another culture are morally irrelevant to the point they're trying to make? It feels like it's a 'get out of jail free card,' in that they deny any chance that morality can be relative.

In particular Alistair Norcross, in his paper 'Puppies, Pigs, and People: Eating Meat and Marginal cases' addresses that the main example of the paper may not be relevant culturally in certain parts of the world, but that fact is morally irrelevant to his argument. It feels like a huge cop-out and I feel as though he makes that claim because it would ruin his example otherwise.
Is there any way to circumvent this trap, or is the author's view of whether or not morality is objective the only thing that matters in a paper of this nature?
Or perhaps I'm misunderstanding something?

Link to Norcross's paper if anyone cares to peruse it or is unfamiliar with this work: http://www.colorado.edu/philosophy/heathwood/pdf/norcross.pdf