I seriously doubt that he wanted to kill his mother's friend, his fascination with Travis the chimp was most likely a product of how he personally felt - an animal that was indoctrinated into a society it doesn't belong in, who would consequently also end up "snapping". But there's no way of knowing if Adam actually knew how similar he was to Travis, he probably just felt that the story fit his idea of culture being inherently bad. Also, there's been 15,000,000 rumors about Sandy Hook and the Lanzas in general since what happened, it's inevitable people will say they know something others don't about the case, so unfortunately we would have to take this whole this with a grain of salt. But considering Adam's issues with regulating his anger, it wouldn't surprise me if he'd threatened violence on his mother in the past, even if he didn't mean it at the time.