While I personally write off the two AVP movies as movie studio money grabs at an established franchise; the fact remains that the Xenomorph social structure is akin to that of an ant or bee colony.

If we go further into this imagined scenario then we can derive the fact that all ant/bee colonies are made up of female both fertile or infertile.

A single male Xenomorph would have to make an appearance at some point to some how impregnate the fertile female and then die.

However, as this is an alien species it could just as well be explained away that it produces viable embryos asexually.

A simple change to the script, such as the Predalien impregnating all humans it encountered (which makes a lot more sense for a species trying to survive), would remove this argument entirely.

I guess it boils down to a single realization: Colin and Greg Strause are dicks (Directors).