so, if you understand morality as an evolutionary process - neither absolute nor relative - then how do you apply that understanding in real life?
the homosexuality example was used in the video, and i don't like the way that chomsky handled it. he should have been a little more firm about individual rights at the expense of a culture, because, really, fuck your stupid culture. and, fuck my culture, too.
abolish all culture.
but, let's say that you have this issue where you have this homophobic muslim refugee showing up from an arab country which has historically had scarce resources (what is going on in the region may be described precisely as adjusting from scarcity to plenty) and a system of laws that reflects it, into an overwhelmingly liberal country like canada, which is overwhelmingly liberal precisely because it doesn't need or have any meaningful restrictions on access to resources at all. this may not be all that hypothetical.
you would certainly not want to tell them that they have a right to maintain their culture in a time capsule, and that it's ok if they hate queers because it's their culture and i'm white. that's a disgusting attitude towards everybody - it's caving in on queer rights due to the soft racism of lowered expectations for the primitive arabs. that's what "cultural relativism" is, in real terms: it's wholly, fully, absolutely through and through racist.
likewise, you wouldn't want to sit there and lecture them about the superiority of liberal secularism over muslim backwardsness, no matter how true it may actually be. you don't get anywhere by pushing your perceived superiority in somebody's face.
rather, what you need to do is explain to them that the reason that their religion persecutes queers is that it was developed in a region that has historically had real levels of scarcity. and, the historical scarcity in the middle east is very, very real. it's not the artificial scarcity of western capitalism. it's people dying of starvation, people collapsing due to drought - sometimes due to war, and sometimes due to climate and sometimes due to mismanagement. queer people do not breed, so harsh decisions about resource management required them to be excluded, in order to ensure that the breeding members of the tribe could carry on. there is no such scarcity in canada, so there is no basis for those rules.
if the refugees are reasonable, they should understand this and modify their prejudices. but, if they react with "MUH CULTURE!!!", then the new society has the right - dare i say obligation - to exclude and ostracise them. there is no reasonable argument to hold to concepts of relativism, at this point, now that we've dismantled them using science. that is no longer cultural relativism, but base cultural conservatism, and should be resisted at all costs.
as for today, the oil wealth in these states makes it difficult to generate arguments to hold to the primacy of their books. with the exception of the horn of africa, i am not aware of anywhere in the region experiencing serious scarcity to the point where persecution of homosexuals can be contemplated as rational. criticism of these regimes should consequently not be muted under arguments of "cultural relativism" - that is just a reduction to "they don't know better", and is consequently an expression of white supremacism.
as an aside, the naturalization of morality has an important consequence: it was the last thing that science needed religion for. now that we have a fully naturalistic understanding of morality, we can dispense with religion altogether.