Bethesda will likely not do this. Not unless they are working on a DLC that adds an official dremora race with a questline extension that explains why the guards at Helgen do not kill you the moment you set foot off the wagon without bothering to check the lists or order you to the block.
Clearly his true nature was disguised by an illusion.
You could fiddle around with the settings in Audacity until you get something that sounds Dremora-ish, then record your own shout words...