I know that the Ayleids in general weren't Daedra worshippers (many Ayleid ruins have statues depicting Auriel flying away from Mundus and Oblivion back to Aetherius) but it doesn't change the fact that the ruler of White-Gold was in fact a Daedra worshipper, yet did not bother deactivating the Tower to allow an Auroran army to invade.
Or does White-Gold only apply to MD's Oblivion sphere?
But he did summon an Auroran army.
And then came the storming of White-Gold, where the Ayleids had made pact with the Aurorans of Meridia, and summoned them, and appointed the terrible and golden-hued "half-Elf" Umaril the Unfeathered as their champion… and, for the first time since his coming, it was Pelinal who was called out to battle by another, for Umaril had the blood of the 'ada and would never know death.
There is a *subtle* difference, after all, between being allied with a daedric prince and having them aid you in battle, and turning the entire world over to their power.
Any good leader would know that allies aren't to be entrusted with too much power. Byzantine Emperor Alexios Komnenos asked for western help. But he didn't let the Crusaders into Constantinople (and for good reason).
Umaril was no Mankar Camoran. The Ayleids didn't want to overturn the existing order. They wanted to maintain it.