23-year-old Isaiah Lee did an interview with the New York Post, and explained his reasoning for hopping up on the stage and attacking the comedian -- and wouldn't you know it ... he says he was, in fact, offended by Dave's material, and wanted him to know about it.

Lee is quoted as saying, "I identify as bisexual … and I wanted him to know what he said was triggering." He adds, "I wanted him to know that next time, he should consider first running his material by people it could affect."

Dave is reported to have addressed his transgender controversy that night before Lee allegedly rushed the stage -- talking about how he didn't have a problem with trans people, until now ... when he says they took his 'Closer' content out of context and warped it.

Here's another element that apparently sent Lee over the edge ... jokes that Dave apparently made about homelessness, which Lee says personally hurt him -- as he himself had experienced it at a young age.

Lee says, "I’m also a single dad and my son is five. It’s a struggle and I wanted Dave Chappelle to know it’s not a joke." Plus, jokes earlier in the night (made by an opener, it seems) talking pedophilia rocked Lee as well. He says he was sexually abused as a minor.

On his gruesome injuries, Lee said ... "They spat on me and twisted me as if on purpose." He also acknowledged having the fake-gun-turned knife on him that night, adding Chappelle asked why he did it. Lee says ... "I told him my mother and grandmother, who fought for his civil rights to be able to speak, would be upset at the things he said."

All of this is a new and different twist on Lee's motives. As we reported, Chappelle has said Lee told him backstage -- before he was arrested -- that he'd rushed onstage to draw attention to his grandmother's plight in a gentrified neighborhood in Brooklyn.