^Or maybe they were. That laser wotsit could have been some kind of stasis or nullentropy field that protected the eggs while the Jockey's corpse was mineralised. Still, though it's been a while since chemistry class but I think a bigger problem wouldn't have been the time it'd take but the environment. Wasn't the atmosphere of Acheron mostly inert gasses like argon? Don't you need something a little more reactive to get that kind of process moving?
Of course that assumes that the inside of the ship had been de-pressurised for most of the time and doesn't take into account all the particulate matter in the air....if that even makes a difference.
Of course that assumes that the inside of the ship had been de-pressurised for most of the time and doesn't take into account all the particulate matter in the air....if that even makes a difference.