This is a tactic typically invoked by people with a anti-trans agenda. Gender, sex and sexuality are in fact multi-dimensional things with some broad clustering.

Either the argument is, "Gender isn't real, all cultural norms stem directly from biology." Obviously and trivially false. Or the argument is, "Gender should be destroyed as it holds people back," which is just a semantics game to penalize some LGBT+ people choosing taxonomies to describe their experience that other people don't like the visibility of."