If we take the view of the theory that presumes that it was the drawer of the family tree who associated the Kokubun clan in Mutsu with Tanemichi KOKUBUN, a Kamakura gokenin (an immediate vassal of the shogunate in the Kamakura), Tanemochi would be an imaginary figure created to relate the Kokubun clan to Tanemichi KOKUBUN.
系図作者が陸奥の国分氏を鎌倉御家人の国分胤通に結びつけたのではないかとみる説からすれば、胤茂は系図をつなぐために作られた人物ということになる。