how so?
Actually, the quote itself was coined by Shirin Ebadi, a human rights campaigner and Muslim lady from Iran.
Basically, the idea that all cultures are inherently equal is something that she and I personally don't agree with.
Here is how she said it in an interview:
The idea of cultural relativism is nothing but an excuse to violate human rights. Human rights is the fruit of various civilizations. I know of no civilization that tolerates or justifies violence, terrorism, or injustice. There is no civilization that justifies the killing of innocent people. Those who are invoking cultural relativism are really using that as an excuse for violating human rights and to put a cultural mask on the face of what they're doing. They argue that cultural relativism prevents us from implementing human rights. This is nothing but an excuse. Human rights is a universal standard. It is a component of every religion and every civilization.
I came to support this idea when I argued with a Christian man who said something along the lines of, "Christianity discriminates against gay people, was used to advocate slavery and used to call people criminals who left or disobeyed the church". To which I said that in Islam, Islamic countries or societies, gay people are still killed and apostasy is still dealt with by death... He said, "what right do we have to interfere in their culture?"
Basically, the idea of cultural relativism is to excuse things we would otherwise consider completely despicable here from a human rights perspective.