[FBD]

Tenth Amendment:
"Powers not delegated to the United States by the Constitution, nor prohibited by it to the states, are reserved to the states respectively, and to the people"--that's us.

[sinkspur]

But, what's Moore going to say when Massachusetts allows gay marriage, then goes to Alabama and demands that Alabama recognize the marriage?

Alabama will point to the Defense of Marriage Act, and, I predict, the Supreme Court will throw it out.

What would Moore do then, when his own state will be FORCED to accept gay marriages, even if they don't want to?

It won't matter what Alabama decides. The 14th amendment will force Alabama to accept these gay marriages, even if they don't perform any themselves.