From Slate:

This is not even a straw man; it's some loose straw the writer is throwing in the air while yelling "Look at that man!"

Funny line, but it may be that it's not a straw man, because it's just not a straw man. Benjamin explained in the NYT that he is boycotting hetero-sexual weddings on the grounds that it is unreasonable for him to "financially and emotionally invest in a ritual that excludes [him] in all but five states."

The response to this, he says, is that his friends take him to task for foisting his political agenda on others. he seems to see their argument as:

P1. Your refusal to come to my wedding is foisting your political agenda on us.

P2. You should not foist your political agenda on us.

C. Therefore, you should not refuse to come to my wedding.

His response is that P1 is false. It is not just a political agenda, since his desire to be able to marry is a personal issue not a political one. He then accuses heterosexual supporters of gay-marriage of having a double-standard.

They’re proof of a double standard: Even well-meaning heterosexuals often describe their own nuptials in deeply personal terms, above and beyond politics, but tend to dismiss same-sex marriage as a political cause, and gay people’s desire to marry as political maneuvering.

Scocca asks "Who are these many straight people Benjamin claims to be describing?" The answer isn't hard to find in Benjamin's column:

Though Zach falls into that slim majority, he scolds me for being “peevish.” He says he resents me for blowing off his special day, for putting political beliefs ahead of our friendship and for punishing him for others’ deeds.

Their joy in their marriage is personal, and they take personal affront at Benjamin's refusal to take joy in their marriage. But, they think the objection to taking joy in an institution that forbids recognition of his own relationships is merely a political issue, and he replies that it is just as much a personal issue to be invited to celebrate an institution that he is excluded from.

Is this a straw man? Doesn't seem like it to me. But, neither is it a handful of straw thrown in the air. If someone accuses you of politicizing their wedding, it seems reasonable to deny that the issue is political rather than personal.

Is it a good argument? I'm not sure about that. I don't see that one guy is "proof of double standard." And, that might be where Scocca feels uneasy: Benjamin seems to draw some broader claims from his disagreement with his friend, and it's not clear that the broader claims are connected in the same way that the claims are connected in the disagreement. And second, in order to be a double-standard the judgment has to be about the same sort of case, and it isn't obvious what the more general case is.