Gender is imaginary

Its a public perception. I wouldn’t say its “imaginary” any more than facial expressions or ethnic complexions.

“I don’t look angry, because anger is imaginary” doesn’t address why you’re beat red with steam coming out your ears.

The complex plane allows for a geometric interpretation of complex numbers

Geometry is a good tool for describing points relative to one another. “You look more/less <thing> than <reference point>” is as valid an observation in terms of height or weight or degree of tan as gender. Also very easy to be wrong, because of your own biases and misconceptions.

But these are all things you can observe and report and evaluate from some objective framing.