Your reference is not official because it's not written by the author, so it's invalid. Now, if according to that reference that Naruto's healing powers came from his RSM and not the Yang Seal that Hagoromo gave to him, then Naruto would have regenerated his arm and Sasuke's arm too instead of regenerating via Hashirama's cells. Your reference in that case is contradicted by the official source (manga).
You haven't questioned the source itself and have not looked in the official documents of the manga to question what that particular source said. There is no contradiction. Naruto's RSM came from combining the Chakra of all 9 Biju's, because he's, in a sense, Jubi's Jinchuriki. Hagoromo gave him the Yang Seal which contained his Chakra for Six Paths Chibaku Tensei, but that seal also granted him healing powers; after sealing Kaguya, it returned to Hagoromo and Naruto no longer has the seal's power - half of Hagoromo's Chakra and healing properties.
Don't let your quickness cloud your judgement. Question the source and look at what the official establishment (manga and databook) contradicted.