To be fair, much of the concern over the Syrian migrants is more to do with their religion and culture then their race, per se. Note that some of the Christian leaders who spoke out about this are willing to take in Christian migrants.
Also, a nitpick about whether the marriage of Moses to a Cushite woman was an example of polygamy, as stated by the author of this article; it may well have been, but other than the “Zipporah was the Cushite woman” theory, I’ve also read the theory that Moses’s first wife Zipporah may have died during the Exodus, leaving him free to marry the “Cushite woman”.
Interestingly, the “Prince of Egypt” film and many other popular modern depictions of Zipporah do depict her as dark-skinned. And there actually is a plausible reason Miriam and Aaron might have spoken out against Moses’s marriage so long after it actually took place. Moses met and married Zipporah during his initial exile from Egypt. She did accompany him partway back to Egypt, but then he sent her (and their children) back to her father. She later re-united with Moses after he led the Israelites out of Egypt into the wilderness. So, Miriam and Aaron did not actually lay eyes on Moses’s wife until then.
Though I agree that even if Moses was a polygamist, this doesn’t undermine the point.
BTW, while I do NOT buy into these beliefs, I’ve also recalled attempts by those who oppose inter-racial marriage to explain this passage away, by stating that God punished Miriam for insubordination, or merely for gossip, and that the fact that He did so, says nothing about whether he approves of inter-racial marriage or not. (It reminds me of the “God struck Onan down for refusing his duty to provide descendants for his brother’s line, not for masturbation or contraception” arguments…)