How dumb were Faris and Karine

They did more idiotic BS in a few minutes than most people do in a whole movie.

-When Karine brought a sick Ledward back to the ship, did it it not occur to her or Faris not to let him on the ship? Surely there's protocol for that?
-Faris locks Karine in the sick bay with Ledward, even admits she herself could be infected, but evidently not sick enough to lock herself in the bay with them.
-Karine thinks hugging Ledward while he's convulsing, after he's clearly contracted something on a alien planet, may help make him feel better.
-Karine slips in the blood.
-Faris comes back in to shoot the baby alien and effs it up by also slipping in the blood.
-Manages to get away, gets chased by baby alien, and blows up the ship while in the process of trying to shoot baby alien.

How did these 2 get picked to go into outer space.