Denial is the first stage.
In universe even going back to when it came out in 1986 and disregarding real life and all other media, they have cracked artificial general intelligence and don't need to send humans to investigate something which means by default that they have non-sentient robots/androids that could do the job too. All they gotta do is have them scope out the whole complex. Even if they still have human soldiers for some reason they don't need to go in first, send an android scouting party.
"Uh sir, our android team swept the whole complex, everyone is dead but one girl, they're bringing her back, also there's a nest of dozens of 6 meter tall hostile alien organisms, shit loads of like, eggs? Ripley wasn't lying. There's no one to save and we couldn't even fire our weapons in there anyway. Fuckin' place is a death trap."
"Well shit."