Given his bio, I guess he wanted someone to end his miserable existence. He was basically a homeless junkie with a record of various violent and sexual assaults. That's why he was goading armed people with "shoot me, n***er!" that night.
shareDude was clearly off his meds.
If someone did that to a police officer, it would unquestionably be ruled as suicide by police.
Something I only found out about tonight, or realized I suppose is more accurate as I've seen the footage numerous times. At the gas station before Rosenbaum starts running his mouth with N***er this N***er that, he kind of gets in the face of a dude in green shirt, a cap and a slung AR. It stands to reason that when Rosenbaum ambushes Kyle later that evening, he's mistaking Kyle with the dude from the gas station.