He may not have been eloquent but he's obviously making a valid point about human physiology and the role it plays in man/woman relationship vs man/man or woman/woman relationships.
The reality is that the forward momentum of the human race has relied on the nature of heterosexual relationships since creation. Whether you believe it is by God's design or via evolution, it is the reality. It's a valid point when discussing the biological onsequences of same sex relationships and heterosexual relationships.
Obviously though it's a purely academic argument. Anyone who actually thinks we need to put people on an island to understand that they won't reproduce is stupid. Of course the whole thing could end up being like Jurassic Park and they surprise us all.