I agree that Oram's actions were a stretch. The fact is, David's behaviour is at the very least incredibly suspicious, and people have been dying as a result of strange alien life for the previous few hours.
"I've been alone on this planet for ten years playing God. By the way, look at this egg. Go on, lean in and take a really good peek!"
I don't buy it. People were snickering at it at the premiere, and Ridley was in the room.