The reason for that - as we learned when we first entered the place and found all those corpses - was that everyone kept coming at it with armies.
i actually think those were all the droids guarding it and when you do the precurser to the quest you disable them all allowing u to pass in.
He didn't want the Sith OR the Republic getting their hands on that tech, it was too dangerous. Revans plan was to build an army and a unified galactic empire that he could rule and destroy the True Sith with. When that all went to pot he just left the tech there since he didn't think anyone could get to it.
but the technology seems to be a piece of the star forge i beleive.