<< I thought you had said Carlson's collusion really bothered you (plot-wise) <<

Yeah, it does. Carlson's a big dope to trust the Xenomorphs IMHO -- and especially when they kidnap his girlfriend AFTER he's promised to trust them and to keep his lip zipped (which, for no good reason, he doesn't)! For me, there's a little too much unmotivated, hard-to-explain activity on ALL sides, that's there only to keep the story awkwardly lurching forward.