[z64555]

Or maybe they're GTI operatives who went back in time to destroy the Vasudans before the Vasudans even existed, but went back too far and ended up destroying everything except the Vasudans instead, and were subsequently destroyed by the Shivans, leaving behind the key to both human and Vasudan survival.

seems legit.

[SmashMonkey]

if that was the case they'd just be sitting in their spaceships playing the clarinet over loudspeaker into subspace all day

Maybe that's what their sin was. And I don't blame the Shivans for wiping them out: There's only so much of the duck-choking sound of a clarinet permeating subspace that one can take.

[Vrets]

Or maybe they're GTI operatives who went back in time to destroy the Vasudans before the Vasudans even existed, but went back too far and ended up destroying everything except the Vasudans instead, and were subsequently destroyed by the Shivans, leaving behind the key to both human and Vasudan survival.

This is airtight...I consider this to be canon.