Gender locked race?

[JunseiKei]

Male miqos are supposed to be rare in lore and they're one of (if not THE) most popular male player character combo

You can't really control the players' choice of race and gender combination. However, FFXI did make a gender-locked race before. Two, actually. Galka were males only while Mithra were female only. Mithra having Viera's stipulation that males were rare and basically kept in villages for breeding.

They revealed male and female Au Ra at the same time...

Yup. That's why I said it'd be in very poor taste if it were planned to be male and female, but only show females, especially if it came down to "the males weren't finished yet." Base models should be done already. 5 months is not that long of a time in development for a game.