After wading through all these comments (which I realize are old now) I think it might be helpful to bring up something my favorite English teacher always used to tell me. When we read and analyze poetry, we must do so considering the speaker's voice, and not the poet's voice.
People who write poems have the freedom to invent personas (and often do), so we must never assume that the poem itself is based exactly on the personal experience of the poet. Many poems are directly related to the poet's personal experience, but some are also a mix of personal experience with invention, or even 100% invention and 0 direct life experience. (In other words, you could write a song from the perspective of someone who's been raped without actually having been raped yourself. It would be incorrect, then, for people to assume that you, the poet, had been raped. It is your speaker, your character, who was raped.) Also, as poets mature and gain skill, they often tend to branch out and write from different perspectives.
I think this can and ought to apply to Reznor's lyrical work. My English teacher would crack us on the head if she found us trying to analyze a person's personality based on his lyrics.
Aside from that, I think it's difficult to take bits and pieces from interviews and try to determine someone's personality type. As was mentioned, none of us actually knows Trent Reznor, and we probably perceive what he's like based on what his art means to us personally.
