Thanks for the link.  I watched Fr. Scalia's talk in its entirety.  He's a very good speaker, but at some points in his logic he opts for simplicity where nuance would have put him closer to reality.  

To use a metaphor, Isaac Newton's view of the world relies upon the simplifying assumptions that space and time are absolutes.  It turns out that while these assumptions make good sense in most circumstances, they don't work for your GPS devices.  You have to use Einstein's field equations for the GPS system to work.  

Similarly, the Church's teaching relies on the assumption that there are only men and women.  While that is mostly true, reality is more nuanced.  To give the most dramatic example, one in 20,000 men are born looking like a woman because a particular gene is missing.  Gender is even more genetically complex, and this affects the "orientation" of one in every twenty-five people.  I wonder what Fr. Scalia's talk would look like if he updated his facts.