.There's also value in catering to the common parlance rather than being overly technical when you're trying to engage the casual fan, and the casual fan thinks Xenomorph = XX121.
.Yep. Alien can many things to the average punter. If you say Xenomorph, any familiar with that term knows exactly what you're talking about.
I'm afraid both of you may probably be right on the mark here, unfortunately -- the game does indeed seem to be settling for the lowest common denominator, rather than trying to be stringent, or "correct".
One might be curious as to whether this is (a) a conscious effort to tone it down to a "casual" fan level lest people get scared off by TMI; (b) a conscious effort to avoid raising the hackles of fans who are emotionally invested in the commonly accepted paradigm; (c) because the game's authors themselves are just casual fans, and simply wrote what they "knew"; (d) the background research being capped at a minimum level for cost efficiency, because, hey, the "hardcore" fans will buy it anyway, so we don't need to cater to them; or -- perhaps most likely -- (e) simply written from the material that the Company (i.e. the property holders) provided the authors with, and that they thus were contractually obligated to stick to.
Whatever the reason, I personally feel it's a pity. Publishing the game presented a golden opportunity to address issues arising from misconceptions or just sloppy thinking that had taken root in the fan community's "world building", and e.g. rectify terminology like this, and generally bring the material closer to the world we actually see in the movies.