I don't necessarily disagree with the argument that a free market enthusiast should desire unions. I disagree that a free market enthusiast should desire unions in their current form, which we both agree is far from a free market.

In other words, I don't think it's unreasonable to say "Device X would be desirable in ideal situation Y, but as the current situation is far from ideal, device X currently does more harm than good".

And again, I don't necessarily personally believe that to be true of unions.