Why wouldn't they?
They haven't won me over t'ill I see Giger's Alien.
But everything looks pretty fantastic otherwise.
I think I'll just pretend the AVP Aliens are A:R Clones as are any eventual AVP:R designed Warriors can be the Warrior-Clone equivalent.
Not to be a downer, but I really don't think they're gunna make the Giger version at all.
They already described their AvP style drone as Gigers Alien in one of the interviews. That model may well have been aproved by Fox under that description.
Given everything to come out of the franchise lately has had digitigrade legs and no back horn, I strongly suspect that the official Fox standpoint is now that the AvP [movie] designs are official and the former arangement was purely a tec limitation.
Finally, in miniature form (its only a little taller than 28mm) the Giger alien would not be significantly different from the 'infant warrior' other than the tail, horn and lower legs, and as such might not be deemed cost effective to produce. You could always custom it.
Edit: In review I actually just realised that many of the minis (as opposed to the concept art) for the most part have plantigrade legs in dynamic posing, which is nice.