Gay couples immigrating here??!?
I don't know the numbers, but I would guess, on a common sense basis, that same-sex married couples are somewhat more likely than average to have two people working outside the home.
Social security is a rip-off for single people and a break-even proposition for married couples who both pay FICA. Social Security is a windfall for "traditional" couples. (It really is still a 1930s widow's pension plan in terms of how it redistributes wealth. It takes money from single people and gives it to elderly former stay-at-home moms. And that may be fine, since widows have to eat just like anyone else. I am noting the real math of SS, not lodging a complaint.)
Given all of that, a gay immigrant couple probably, on average, does more to shore up Social Security than a heterosexual couple. I would guess such couples also have a more beneficial GDP-per-capita effect.
So of course, let's keep them out...
The dumb-assedness never stops.