The sacrifice engineer is I think that one we have seen many times in Alien. Therefore sacrifice. He sacrifices himself to protect cargo (alien eggs) for whoever wil find them. Maybe Aliens are that precious for Jockeys.
But as we've been told repeatedly, this movie will not directly connect to Alien.
I know that
But, i think , what i have mentioned above is the Alien DNA that Scott is talking about in the last minutes of movie.