I mean that's just completely false. The Act requires the U.S. federal government and all U.S. states and territories to recognize the validity of same-sex marriages.

From the Act:

Congress finds the following: ((a) In General.--No person acting under color of State law may deny-- (1) full faith and credit to any public act, record, or judicial proceeding of any other State pertaining to a marriage between 2 individuals, on the basis of the sex, race, ethnicity, or national origin of those individuals; or (2) a right or claim arising from such a marriage on the basis that such marriage would not be recognized under the law of that State on the basis of the sex, race, ethnicity, or national origin of those individuals.

Seems pretty clear, no?

Again I'm not trying to say this is a fait accompli and we can just sit back on our laurels and consider it done. But it's a hell of a lot better than Russia's law.