Board Thread:Naruto Discussions/@comment-34661853-20181122024542/@comment-34661853-20181122104237

In the anime black Zetsu states that Kaguya had the power of Shinjuu and that to protect Kaguya, Shinjuu became Juubi. Of course Juubi may have joined Kaguya at some point, but I think Hagoromo and Hamura have sealed to Kaguya (when she was separated from Juubi) and then Hagoromo became Jin.

It doesn't make sense for Hagoromo to have become Jinchūriki of Juubi (Shinjuu and KAGUYA), because in history, when Kaguya was sealed again, only she stayed sealed, and there were 11 forces there, the 9 bijuu, the Gedo Mazo and the Giant Rabbit with the rinnesharingan on the forehead (that was Kaguya), ie Kaguya was an entity separate from the Juubi. The Juubi was the junction of the 9 bijuu and the Gedo Mazo. Then Hagoromo and Hamura sealed only the Kaguya.