>One, that makes no sense. Sex is a classification because it is part of material, empirical reality.

You are fighting a losing war here. Bulter is a post modernist, they don't just disagree with your conclusions, they disagree with the entirety of how you got there. To a post modernist the statement,

" it is part of material, empirical reality."

Is already were they are disagreeing with you. Material, empirical reality either does not exist or is impossible to discover according to them.