By poster boy I was referring to his poetically just messiah identity. (See the OP.)
Regarding Introversion, I actually see him as a clear-cut Introvert based on his interactive style in interviews. He is in the limelight, but I see him as being there in service of his Ni rather than because he craves the attention itself. (Notice how he idealistically refused to give interviews in the Columbine aftermath but simply published the written statement I link to in the OP.) Compare with other image-heavy shock artists (Madonna, say) who wanted all eyes on them but then turned out to have nothing to say.