I hate the dumbass but he's correct. There's still quite a lot of people in the Farms and outside that are desperately trying to convince themselves Chris dindu nuffin and he was totally manipulated into, well, fulfilling the fantasies he's already had for years, which adds a lot to the Bella fuel, people wouldn't care nearly as much about her other crazy behavior if this wasn't connected to Chris, she'd be yet another horrorcow and just now that his mom is weak enough, he was finally able to do it.
He was able to use his book for sex with people with disabilities he bought only for the purpose of fucking her and, gradually, make Barb less and less resistant.
Yes, yes, Bella is a fucking monster, she encouraged these already-existing fantasies but, in the end, it's Chris and only Chris who did this, with full knowledge of it being wrong and the potential consequences.
He's a coward and he's been afraid of consequences in the past which has prevented him from doing other dumb shit but this one that's a lot worse, he magically stopped knowing right from wrong? Do you suddenly forget every other bad thing he's done? The innapropiate behavior towards women? The macing? The Snyder car incident? Was he innocent of all this as well and "just didn't know what he was doing"? At some point, people need to stop fooling themselves.