I agree with you that, because there is no competition in the Diesel "category", Audi automatically get's granted equality in engine power(in terms of FTF). The problem is not that, didn't you read my other post?!
They get the total energy, per lap, equalised by the regulations but they end up with less room for ballast and less flexibility to manage that energy as they are lower in the ERS classes.
Does anybody have any idea of how much weight the extra batteries, on the 8MJ cars, adds on the 919 and TS050? Whatever the battery pack weights on the R18, the rivals have 33% more of that. Would it add up to 50kg and make all cars even in terms of ballast available?! If so, then the Petrols would only have, as advantage, a little bit of better flexibility concerning the management of their power release.
It must be said, though, that I doubt the handicap that Audi has is big. I would guess it to be around 0.5s