Personally I susbscribe to the Nokris as sibling of Crota, it's the only other one that makes even a little sense. For one, I think it logical for an [i]equal[/i] of Crota to be put in that same location rather than his superior, a former king. Second, what would be the reason for his name to be missing from not only the BoS, but also the World's Grave database and every other source the ghost can find? You do make a good counter to the point about Nokris not being erased from time, I certainly can't disprove it. That said, I don't now if we can put the actual physical structure of the Dreadnought (which the statue is part of, and close to the throne-world-inverting superweapon at that) and the BoS definitively in the same category. (And while I fully admit it's a weak argument, we don't have a complete copy of the BoS either.) The books we have are presumably not the originals written in Orxy's own hand. Honestly I'm not sure what the lore explanation of how we came to have them is, I assume that the calcified fragments are akin to some kind of storage media from which we extract the books. Regardless, the BoS and the dreadnought are not inexorably linked and it's not impossible that what basically amounts to a copy of the Hive bible could have been affected by Vex shenanigans.