Dallas ordered the door be opened (in defiance of quarantine protocols - and balled Ripley out for not complying; supported by Lambert) and that they take off without completing repairs.
He was complicit.
I am saying whatever Dallas did Ash was supposed to listen to Ripley. Its the second time that happened . When mother indicated that the signal was a warning he defied her when she wanted someone to go and warn Dallas and co. If he had listened they would not have had this problem . I would assume that warning crew of a possible threat must be a priority. just saying.
OK maybe getting face hugged was still a possibility.
Sorry the statement was actually directed not really at SM but at that post in which was the answer accepted by all on the issue of "letting people aboard" as an act of stupidity answered by SM (and quite correctly) that Dallas was implicit . My point is that should never have happened based on standard operating procedure. So Ash by and large in his capacity as a an agent of the company was responsible in two occasions for letting things happened which shouldn't have, The first setting up the second to a degree. Hence no stupidity. They were coerced by Ash who had a mandate to full fill. Alien is a well written movie.
I don't understand the whole helmet removal issue in Prometheus. Before they removed there helmets Holloway asks David if something is generating an atmosphere and he replies "yes" or "correct". Supposedly David follows Asimov's 3 robot laws like Bishop does. Then someone remarks "cleaner than earth's actually" and David doesn't refute it. When they get to ampule room Shaw clearly tells David not to open the ampule room as they don't know what is is on the rather side. He clearly ignores her and says"sorry" in a sort of "oops my mistake" sarcastic way. Now they are helmetless in a possibly infected room.
What's my point? In both Alien and Prometheus a compromised android sets up at least two events that leads to people being infected. Why is it stupidity in Prometheus and not Alien? Everybody expects the android to protect them. its 2093 isn't it?
as for other issues of stupidity ..............nudge nudge wink wink