They could very well be asexual. We don't much of anything regarding their species. That said, I see why people are associating this new one with a female. Aesthetically, it has more feminine qualities than we're used to on a predator, but ultimately this can be attributed to anthropomorphism. Female predators ( if there is such a thing ) wouldn't necessarily have more pronounced breasts like humans do, nor would they necessarily be more diminutive than the males. For all we know, every predator we've seen depicted in the movies could be female. We just don't know.