moral relativism?

[homegrown]

I read the article on moral relativism and felt it may be helpful to suggest that, if evolution provides a moral sensibility - as opposed to a set of moral values, akin to the innate tendency to learn language that then achieves expression consistent with the environment within which the child is raised, neither relativism nor objective arguments are valid - even while both have something to say.

[The Voice of Time]

Why are they not valid?