That is my belief as well. As to why the Engineer did what he did at the end, here's my take -Walter said:It seems to me that the black goo is more like a weaponized evolutionary compound. It turns things into violent creatures, the function of which I presume is to wipe out a race. It's certainly not as simple as "granting desire," because there's obviously a common physiology that links all of the creatures. We saw earthworms turned into proto-facehuggers, for example. Shaw's "pregnancy" also wasn't terribly different from the incubation period that xenomorphs undergo during their gestational phase.
originally the Engineer's were Earth-bound to actually deliver the payload and to destroy life on Earth. Unfortunately for them, shit went wrong and they could not achieve that (Hologram's evidence of it and also, when they recover the decapitated head Shaw indicates there were signs of change on a cellular level plus the black goo runs out of it's pores when they try to tweak it - so the Engineer's running away were scared of being infected by the goo. The ones infected were piled together with things busted outta them). Now, fast-forward - David and the humans go to wake the sleeping Engineer. He's surprised to see the things he was originally sent off to terminate have found their way here and he freaks out.
There's already a lot of talk about a sequel called Paradise. Obviously it doesn't sound like there will be a paradise at all.
About the goo, it's not that hard to figure out that -
the urns begin to 'sweat' as David said because they were somehow activated when they entered that room, probably heat induced. When ingested by the worms, they turned into acid blooded aggressive bigger worms/ snakes that face-hug in their own characteristic way. When Fifield's face gets exposed to the goo, he turns into an aggressive dude and he's all crawled up outside, reminds me of how the Xeno's shown sitting in Alien/ Aliens. Holloway's infection was changing him as well.
This is a fun read - http://screenrave.com/index.php?option=com_content&view=article&id=24770rometheus-secrets-behind-the-surgery-scene&catid=65:tidbits&Itemid=167
I would've preferred the real gore for that scene from the original script.