Question is pretty self-explanatory. I believe it’s already been confirmed that the Ignika could bring him back to being a Nuva, but what if he were to take another dip in EP? I imagine that the Toa Mata transformed when exposed to it because becoming Toa Nuva was a prerequisite part of their destiny to awaken Mata Nui. But now that Mata Nui is awake (albeit dormant) and the Nuva’s destiny has been fulfilled, would exposure to energized protodermis destroy Tahu, since he’s no longer destined to transform?
It is not known whether he is destined to retransform or be destroyed:
The concept of “destiny” might as well come down to preprogrammed AI and body that is premade with preprrogrammed response to EP, if that’s the case then some beings have receptor-like response when coming in contact with EP, some will have their transformations triggered, some will have their deaths triggered, but that’s my interpretation and I’m not GF.