Not just that, let's think about how an Auriga-contracted egg-hunt might shake out:
Auriga contracts some mercenaries to do an off-the-books job. Grabbing eggs is dangerous without some kind of preparation, so the Auriga tells the mercs vaguely what they're dealing with so they don't f**k it up - the Auriga doesn't get their eggs if all the mercs are dead, after all.
Who knows if the pay is "good", or maybe the mercs start to think they've got a goldmine on their hands and double-cross the Auriga and try to find a higher bidder - assuming the details of the job haven't already leaked and someone on the Auriga flips for the opportunity for a payday, or one of the mercs opens their mouth and corporate interests find out about the job ahead of time and sabotage/intercept it. There's a lot of ways the Auriga could get f**ked, and they'd have no recourse. Shit, maybe it already happened "off screen" and it's not brought up in the movie.
And since you're dealing with Aliens, the mercs could still drop the ball and get themselves killed at any point despite having an idea of what they're getting themselves into. And all of this is irrespective of a hypothetical blockade or quarantine or whatever.
Or you send the mercs in blind with minimal instruction, and hope they don't pull a Nostromo and get themselves killed, or that they get clever and sell out anyway.
Telling a bunch of mercs to capture a bunch of warm bodies and not tell them why is likely to raise less questions and decrease the chances of something going wrong, and that's probably a big factor in why the Auriga did what it did.