The comics started their release in 89. The P2 movie came out in 90. The Alien skull in p2 was actually a nod to the comics, not the idea that inspired the comics. Chris Warner actually came up with the idea and Randly Stradley is the one that ran with it.
From what I remember, it's very murky. The original graphic novel compilation, with the foreword and such, mentions that they were being very careful about not boxing their Predators in, due to knowing 'Predator 2
' production was literally underway (which made the decision to show the shoulder cannons, but have the Predators actively using old-fashioned hand-held explosive guns, all the stranger). At a guess, I'd figure this was the scripting/location scouting/casting phase.
The inclusion of the skull has always been a messy subject. Stan Winston is on record as saying he had no idea who thought of it, but would "like to think" that it was him (on account of thinking it was a very cool idea) and that they were just making up a bunch of strange and extraterrestrial skulls for it. Definitely no mentions of being aware of the comic at the time. Some people have speculated it was a joke, but there's nothing, whatsoever, about the way it was shot, which is even the slightest bit humorous.
So, it's possible that one of the men/women who was working in Winston's team decided to make it up as a nod to the comic sales, but would special effects guys necessarily be aware of sales figures? I'd say that it's just
as possible that, considering how close the dates between publishing and shooting were, that the skull was simply a coincidence. As the guys behind the comic have said, once the concept was mentioned in a production, it seemed like the most obvious thing in the world.
And I know that, back in the eighties, I, for one, immediately imagined what a match-up like that would be like, after seeing the first 'Predator
All those swampy scenes at night just felt ideal for Aliens to fit in, visually.
Unless the person who made the actual sculpt comes forward, I don't think we'll ever have more than speculation and guesses to go on.