I think it was Bishop but he didn't actually know that he was doing it, since he is unable to harm humans or put them in harms way the company probably sent an override signal to Bishop to retrieve an egg for the Bio weapons division, after all he was made by Michael Weyland shown at the end of Alien 3. When the atmospheric processor started going critical maybe the queen layed a queen egg because she felt in danger and had the egg hidden from the main hive and Bishop found it. He put it under the cyro tubes so that it would awake during the journey and facehug one of the passengers and it will be easier to transport the alien through ICC. However the company turned off the signal and went back to normal and has no recollection of what he has done so he cannot tell Ripley like when he told her about Burke's plan by accident and it would serve the company to let Bishop to save the survivors in order to have a host. However the question is when did Bishop do this was it when Ripley went after Newt or when he went to bring down the dropship. I think it was went to bring down the dropship because I think there wasn't enough time to go back and fourth to the Sulaco and find the egg in the hive in 15 minutes. He could have tried to trick the survivors when he was bringing the dropship down as it could have been for the second time to act like he just got there. Any thoughts?
