The problem with Tammy acting like a narc with Greg is that it doesn't make sense with how he represents her now: he talks about her as this amazing, wonderful mother who taught him a lot of things and protected him from his "child rapist" father. She even had a boyfriend named Greg and would have sex with him and scream his name making sure that her son would hear, and went on to give him a full body massage while she was naked too when he was a teen.
According to stories he and other people have told about his period in high school, Crazy Tammy would show up whenever the principal demanded to talk to her because Greg had done some stupid shit, and she would sing "magic" songs that would make the principal leave his precious son alone.
She participated in Greg's videos and often played his girlfriend, and only turned on him when he gave her a house for free and then demanded she paid rent.
That's narc behaviour alright, but he clearly wasn't the scapegoat: he was the Golden Child, the one that can do no wrong and it's the rest of the world that is up against him, which is a way of thinking he has to this day (people are not hating him because he's a rapist, a pedophile, and an abuser, but because they're jealous of his immense beauty and success!). He's completely unable to see the truth about himself, and will argue to death that Billie is a bitch because she didn't want to get chained in his basement for a week. He is a perfect being in a world filled with ugly and dumb people, and it is his duty to criticize them and push them into having eating disorders so that they'll look good for him and will rise at his level.
It's impossible to deny that he doesn't have ideas of grandeur, and the only person who has brought him on this way was the only parental figure in his life, and then it was amplified by his audience. The only reason why he looks like he's losing his mind is because he now has neither of them.