No, it's a same-sex wedding because the two people involved are of the same sex. There nothing inherently impossible about a homosexual marrying someone of the opposite sex, or a heterosexual marrying someone of the same sex. They are unlikely to want to do those things, of course, but they could if they did want to. (And, of course, many people are not exclusively homosexual or heterosexual!)

Millions (billions, if you consider the entire world population) of people believe that the institution of marriage is inherently something that happens between a man and a woman. Just like many people believe that marriage is inherently exclusive/monogamous, or inherently not permitted between close biological relatives, or inherently reserved to people above a certain age, or 1000 other restrictions that you or I may or may not agree with. Is it illegally discriminatory against people with siblings to refuse to bake a cake for a wedding between brother and sister? What about a polygamous Mormon marriage where the husband is taking his 17th wife, would refusing to service that event be illegal religious discrimination?

But marrying someone of the same sex is. It's perfectly possible for someone who is homosexual to marry a partner of the opposite sex, and vice-versa. (And of course, many people are bisexual!)

Look at his submission history and you'll see similar attempts to do that. In his comments he also comes to the defence of an ex moderator of 8chan that had answers other than "no, absolutely not" to whether CSAM should be allowed on it.

https://news.ycombinator.com/item?id=40385450