In & Out/WMG

Jack is gay.
He's the student that reacts most intensely to the whole affair. It might have to do with him being uncomfortable with finding that an admired role model is gay, but also might have to do with him finding a role model for his own homosexuality, and being uncomfortable about how everybody is treating Howard.

And when he started the I Am Spartacus moment in the graduation? It was a test for when he finally decides to come out.