*ahem*I remember talking to a friend of mine years ago, and I said, "Can you imagine the planning, manpower, time, materials, etc. it would take to build something like the Deathstar?"
That guy really must have been a genius if he was so important to its construction.
Actually if you follow the movie's plot, it seems to me that his expertise is on kyber crystals which is needed to operate the Death Star's superlaser. The guy dies at the Kyber Refining Facility on Eadu.