so thinking out loud here will save this for future reference in a time when it is relevent
Mata Nui was never put to sleep in G3, not to mention he will not be in it very much at all.
As I recall, it’s been pretty vague about where Mata Nui fits into G1, but I think the consensus with the TTV at the time was that he would be the father to Karzahni, Ekimu, and Makuta and be defeated by them in a Kronos-like fashion.
In any case though, @TheMOCingbird is right that he will be mostly a non factor in G3
that’s true but it’s Karzahni who reveals the outside world not Mata Nui he will remain out of this