On the audio commentaries, Lucas says stuff like "it takes ten years to get through the (original) trilogy" and "the hand anakin gets at the end of AOTC is the one cut off by Luke at the end of ROTJ." We already know/knew those things aren't true, so his comment on death star is just as suspect. The DS's backstory was complicated enough even before AOTC. The only part I know is Tarkin stealing the idea from Sienar and presenting it to Palps at some point, but then comes AOTC to show that the Geonosians (of all people) were developing it. First off, there has to be some sort of backstory to the geonosians and the death star plans. I mean, the two things just don't go together unless you really start to stretch them. Tarkin's presence at the end of ROTS acknowledges his part of the backstory once again, so this thing with the geos is kinda wierd even if you just go by the movies and ignore the EU.