I feel the same dichotomy. What people said below is correct -- he does not mention sexuality -- but it still tinges what he writes.

In thinking why this is, I have the following to offer: if it was "John Q. Random on Why Software Companies Die", there is a good chance it wouldn't rise to the top of HN quite so quickly. The accumulated reputation Card has is actually important for people reading this article. If this is so, then we must remember some of his reputation is being anti-gay-marriage: it is no less important to this article as is him being the author of Ender's Game.