The word "multicultural" deserves a better analysis. What exactly is a "culture" (besides that for many people it is an applause light), which parts of culture should we preserve and which are free for optimization, whether we can measure a utility function of a culture and whether that function itself is culture-specific, whether cultures can be extrapolated, how much can human cultures be different, et cetera.

The important part is that we are speaking about human cultures, which puts some limit on how different they can be. We should not discuss them as if there is no such limit, as if an arbitrary set of values can be a culture, and each such set is automatically an applause light.

To the extent that humans from different cultures can share values, there can be common values even in the multicultural society. And there can be cross-cultural hypocrisy with regards to these common values.

In other words, we should not model humans from different cultures as incomprehensible aliens. Funny thing is that there two opposite political reasons to do so. The obvious one: racists/nationalists/etc. try to describe the other people as completely alien, to make it easier to explain why we should avoid them. The more subtle one: politically correct people sometimes also describe humans from other culture as aliens, just to signal how tolerant they are; because tolerance to an alien is more difficult, and therefore more noble, than tolerance to a mere human.

In yet other words, the "multicultural" society -- as its greatest proponents and opponents imagine it -- does not really exist. There is just an interaction between different human cultures, which includes a lot of differences, but also a lot of shared values.