I don't see why the Predalien wouldn't be on the Aliens' side. It's no less an Alien than the human-born Xenos. They have the same life cycle, only the host differs. The Newborn on the other hand was less Alien, a freak, and thus was different in many ways. To put the two in the same group is flawed.
Predator's side? That's ridiculous. You don't see human-born Aliens siding with the humans.