What, in your opinion, is the reason the church is supporting him?
Why not, he is a renounced academic scholar teaching in one of the most prestigious universities in the world, and sharing incredibly insightful information about the very real, fallible, human being that Joseph Smith was, as all prophets throughout time have been. Only one person was ever perfect, and he lived 2000 years ago, yet lives today!
You folks think he will be excommunicated for sharing that stuff, quite the contrary.