Why?
More info about the Hillsdate College tax break:
Senate Democrats Blatantly Lied About Hillsdale College
https://thefederalist.com/2017/12/02/senate-democrats-blatantly-lied-hillsdale-college/
There are five or six other collages that would get the break as well. Since they do not take federal funding then it is only fair that their endowments not be taxed.
Hillsdale College does not take ANY Federal money.