I guess if I had a chance to talk to this guy I would remind him that we don't live in a world where gender doesn't exist, and that such a world is not about to invent itself anytime soon.
I could respond to a lot of specifics about your excellent article, but mainly what I'm thinking about right now is a category of objection to social progress rooted in a hypothetical utopia that is highly unlikely to come to pass, at least in the near to mid-term future.
As a trivial example, somebody objected to a recent Prism & Pen article calling for an end to laws to keep transgender women out of publicly accessible women's restrooms.
That somebody objected that it's important to understand and accommodate the fears cis women have of trans women, so we should provide special facilities for trans women to use.
OK, I thought, even if I agreed with that proposition, what do we do in the real world where those facilities don't exist and won't exist anytime soon? It's not like transphobe are organizing massive gender-neutral restroom building programs.
That's what I mean by hypothetical. It's kind of like waving a magic rhetorical wand: "See, I just said some special words that make my position feel reasonable to me, even though those words have nothing to do with how the world actually works."
"I don't see gender" fits into that category, I think. Because that's not the world we live in or will live in. Saying those words is like waving a magic wand and expecting something real to happen.