Some people have questioned whether the Obama Administration's proposal to "Lift all restrictions on transactions related to the travel of family members to Cuba" or "Remove restrictions on remittances to family members in Cuba" would be unconstitutional discrimination based on ethnicity in favor of Cuban-Americans. I don't think so (though of course it would depend on the precise text of the rule, which to my knowledge hasn't yet been set forth).
The rule wouldn't distinguish people of Cuban ethnicity (whatever precisely that might be) from people of other ethnicities. Rather, it distinguishes people on whether they have family members in Cuba. If two German Jewish brothers left Europe before World War II, and one came to the U.S. and another to Cuba, the children of one would be able to visiting the children of the other.
To be sure, the overwhelming majority of the beneficiaries of the law will be Cuban-Americans, in the sense of people who came from Cuba or whose own ancestors came from Cuba. That's what is called in the law a "disparate impact" on Cuban-Americans, here in their favor.
But such a disparate impact doesn't make for unconstitutional discrimination. That, after all, is why the current policy of sharply restricting visits to Cuba isn't unconstitutional discrimination -- it doesn't distinguish Cuban-Americans on the grounds of their ethnicity, though it has a much greater impact on Cuban-Americans than on others. Under the current policy, most people are free to visit their relatives (since their relatives aren't in Cuba), but most Cuban-Americans are much constrained in their ability to visit their relatives (since their relatives are indeed in Cuba). That's not presumptively unconstitutional discrimination because it doesn't facially discriminate based on ethnicity, and isn't intended to so discriminate. The same is true of the proposed relaxation of the travel restrictions.
This also helps explain why there's little reason to think that this facially ethnicity-neutral distinction (do you have a relative in Cuba?) is intended to discriminate in favor of Cuban-Americans because of their ethnicity. (As I suggested above, intentional ethnic discrimination is generally treated by U.S. constitutional law as tantamount to facial ethnic discrimination, and not just to disparate impact.) The proposed change seems intended to do precisely what it facially does -- to let people visit their families, something that the rest of us can generally do without U.S.-imposed restrictions.
So while I can't speak to the wisdom of the proposal, I don't see any constitutional problem with it, or any ethical problem that is related to any supposed ethnic discrimination.