This is pretty difficult to parse - and this difficulty is probably why you've not gotten any useful responses.
If I'm understanding correctly :
As a revenant, when you drop to 0 hp, you have the option to become dazed instead of becoming unconscious.
The feat superior will allows you to save against a dazed effect even when the effect does not end on a save.
Ruling: per RAW (Rule As Written), you are correct. Per RAI (Rule As Intended), ... it's a bit harder to say. On one hand, there's a very strong tradition of not being able to counter self-imposed penalties. On the other hand, it's pretty easy to see how having that feat would allow for that kind of grit.
Personal take: Not sure!
I tend to err on the side of the player. BUT I really dislike being able to counter costs or drawbacks (self-inflected penalties in general). Also, Superior Will is already a crazy strong feat (to the point of being almost mandatory) so I'm leery of giving it even more utility...
Final answer : I'd probably not allow the use of Superior Will, but yeah... I'd probably look at how that character is faring compared to the others - if I felt it lagged behind a bit, I'd allow it. If the character already dominated, I'd not allow it.
It's a hard one!