At another point in the game it tells us that we are standing in front of the corpse of the individual mindflayer who implanted the tadpol.
From this point of view, it could never have been the Emperor.

I don't know Larian's policy on additional content, it's my first Larian game.
But I would be really happy if Larian would now work on the weak points of the plot. And not just "give the NPC standing on the corner the happy ending he deserves".
The Dark Urgeand the Emperor in particular still deserve some more attention in order to correct the one or other unevenness in the consistency.