I've kind of gone by "well, we've been using M16's or a variation thereof, as well as AR's and AK's for nearly 60 years" so in an age where we have both amazing tech (Prometheus) and standard tech (Alien) co-existing, Aliens military budgets would likely be somewhere in between, so it wouldn't surprise me if the pulse rifles were "old reliables" in the Alien universe when it comes to Colonial Marine standard issue material... much like how Hicks still has an old fashioned pump action shotgun, yet the security forces in Isolation have those rad assault shotguns. You've also got different incinerators in nearly every film too with Prometheus' ones being surprisingly the most archaic in design!
This is also just two years after Isolation, so if they're still using the suits in Isolation, I figure they're fair game. Zula isn't going into this crusade needing military gear to begin with either. She's almost there in a consultant role, so a non-combat suit made sense. I ALMOST went with the one in the Marine book, but I just like the old compression suits more. That said, I definitely want to use the compression suits you see in the security offices of Isolation (the ones that use the helmets you see at the start of Alien).
And it's highly likely you'll see the heavy Weyland Yutani marine gear from Colonial Marines (love or hate that game, their design work was spot on), and POSSIBLY the containment suits from Alien 3. It's all dependent on what Brian writes. I don't think you'll see anything quite as advanced as the Prometheus gear... at least not in action.
Also, he's actually telling her that if she's not happy with his services, she can log a complaint.