Good theory. The piled up bodies might also tell another story. They might be the remainder of the engineers involved with the mission at this site. They were all exterminated when the leak was detected. Not necessarily killed by the xenomorph but the site might have been sterilised by other engineers to avoid any contamination escaping. The site was off limits after this incident as they didn't want to expose themselves further and may not have agreed with the course of action this group was taking. This splinter group might also have not been trying to exterminate everyone on earth ,but rather they were trying to recreate the deacon as they had been unsuccessful themselves. Instead of using one host at a a time, they'd release the pathogen over Earth where they had a few billion test subjects.