I mean, yea sure he hates him, but did he bully him? If we are going to take Cobra at his word then I guess he beat a kid with a metal chair, smells good, can control things with his mind, summon thunder storms, and wish people into traffic collisions. I do not doubt he hated another retard, probably for being bullied by him, I just doubt Cobra bullied someone IRL. Being kicked out of the bar on Halloween is a perfect example, he is a pussy. The guy who is bullied by passing strangers just does not strike me as the school badass.
Now if Carl was a girl, you would have an easier time convincing me he did anything other than "leave me alone dood I'm autistic".