Ginyu actually has no real concept of gender, he abandoned his original body when he was rather young, and never really looked back. Typically, he usually shifts between masculine / stronger bodies because those are what most often reveal themselves in battle, hence making them easier to swap between. Given the chance, he doesn’t mind taking female forms, as he’ll take whatever opportunity he will get for survival, but ultimately, he doesn’t care, either way. He’s taken so many forms that it genuinely doesn’t matter to him.