I rewatched the MU Movie Trilogy last night and I had a revelation.
(Tahu Mata's Golden Hau was not the true Golden Hau, it was a spare)
Think about it, Mata Nui had multiple fail safes. The Golden Armor though made for Tahu, was most likely given to Lhikan to prevent it from being stolen. Lhikan may have known about the Golden Armor plan, so he took his mask off and pointed to how to escape Metru Nui, so they can give the mask to Tahu as he arived. Lhikan had golden chest, 2 golden shoulders, and his shield was gold. But because Jaller's mask broke, the only spare they had was Lhikan's, so they gave it to him, and Jaller adopted some traits from Lhikan like sacriface oneself to save others. When Jaller died, they islanders kept the mask, and Mukuta was most likely manipulating Takanuva when they were Takutanuva into using half of each of their life forces to manipulate the mask into growing a body, and transporting his spirit back from the Red Star. When Takanuva escorted them to the shadow barrier, Karzahni stole the golden Hau because he knew how important it was, meanwhile Dume hid Lhikan's body just in case his armor would be needed to serve their true purpose. And I believe one of the Toa Nuva tasks was to recover Lhikan's Hau, once they did they completed the collection of golden armor.
The rest is history...