If you say "I believe X, because A, B, and C," then if you want to disagree with that statement, you dispute A, B, and C.

Besides, his "thesis" is vague, and poorly worded. It is, essentially (and this is me boiling it down to as concise as possible):

"Liberals claim to be objective and scientific, yet are willing to call a person with a Y chromosome a 'woman.'"

The rest of his post is just rambling anti-trans stuff..

And his point is incredibly easy to counter- look up the difference between the definition of "sex" and "gender," and realize which one people are using. No one is suddenly pretending that a Y chromosome suddenly grew a leg and turned into an X.

He brings some creationism stuff into the thread in later posts, which was kind of random, and led to a side discussion. But that's another thing- people are discussing his arguments as he presents them, but they're being presented all willy-nilly, and they're not particularly coherent.