Hence why I say at the end of the year. I can see Spoiled procing right after he leaves and him insisting on coming six months and doing nothing but indulge in the luxuries of the Isle of the Elves again.
The Emanation also needs to die on a fire.
We also have no reason to believe that we can choose Extra Diligent again if we retain Spoiled. Nameless could easily enjoy Necromancy Research now while it's novel but be bored to tears by it in a year's time.
And the reason is still critically important. We know that Nameless is much slower at Necromancy Research than the lich, and that the only way to make meaningful progress in a reasonable timeframe is with it's assistance:
Nameless being diligent only matters in so far as it changes his personality and so the lich's. It only seems worthwhile paired with I'll Face Myself.