Maul isn't dead, canon, by Lucas' consent. There's plenty of reasons why he would not like to use him in aotc and rots. Apparantly Lucas told Jackson that he's fine with Mace being alive and in hiding. So that's not canon (yet), but by Lucas' consent, apparently?
Anyway, you can have your own version of anything, until you wanna discuss it with others, then canon is the only possible arbiter, and clone wars and rebels are canon. Maul plays quite a part. In the movies there isn't really a place for him. I used to wish dooku had been maul returned, but that doesnt work, because Dooku is pulling strings Maul couldn't have. He also can't replace Dooku nor Grievous because that would out the Sith as leading the seperatists, which destroys their galactic appeal. So that's not much of an argument.