Well, to be honest, this is pretty well established and not at all controversial in the field of child psychology. I actually don’t give a shit if you believe it or not. I’m not looking for a debate.
You say this as if occurring earlier would mean that it was less of a predictor of later antisocial behavior. Significant early antisocial behavior is more predictive of persisting antisocial behavior than antisocial behavior with an onset in adolescence. Look into the literature, particularly the work of Rolf Loeber, Tammy Moffitt, and of course the DSM distinction between childhood onset and adolescent onset CD. Tammy Moffitt’s work on life course persistent versus adolescent limited antisocial behavior is pretty well-established too, including a study showing genetic underpinnings for the life-course persistent type of antisocial behavior.
Google Scholar shows many, many studies of the relationship between animal cruelty and later antisociality. You could not have read through the findings and drawn the limited conclusion you just did. However, I’ve culled from PsychInfo a set of references that describe the links between animal cruelty and later antisocial behavior:
Lahey, Benjamin B; Waldman, Irwin D. Personality dispositions and the development of violence and conduct problems. [References]. [Book; Edited Book] Flannery, Daniel J (Ed); Vazsonyi, Alexander T (Ed); Waldman, Irwin D (Ed). (2007). The Cambridge handbook of violent behavior and aggression. (pp. 260-287). New York, NY, US: Cambridge University Press.
Roberts, Kim. Interlocking oppressions: The nature of cruelty to nonhuman animals and its relationship to violence toward humans. [References]. [Book; Edited Book] Waldau, Paul (Ed); Patton, Kimberley (Ed). (2006). A communion of subjects: Animals in religion, science, and ethics. (pp. 605-615). xxxi, 686 pp. New York, NY, US: Columbia University Press.
Petersen, Marie Louise; Farrington, David P. Cruelty to animals and violence to people. [References]. [Journal; Peer Reviewed Journal] Victims & Offenders. Vol 2(1) Jan 2007, 21-43.
Waldman, Irwin D; Singh, Amber L; Lahey, Benjamin B. Dispositional Dimensions and the Causal Structure of Child and Adolescent Conduct Problems. [References]. [Book; Edited Book] Krueger, Robert F (Ed); Tackett, Jennifer L (Ed). (2006). Personality and psychopathology. (pp. 112-152). xii, 402 pp. New York, NY, US: Guilford Press.
Ascione, Frank R. Children who are cruel to animals: A review of research and implications for developmental psychopathology. [Journal; Peer Reviewed Journal] Anthrozoos. Vol 6(4) 1993, 226-247.b
Felthous, Alan R; Kellert, Stephen R. Childhood cruelty to animals and later aggression against people: A review. [Journal; Peer Reviewed Journal] American Journal of Psychiatry. Vol 144(6) Jun 1987, 710-717.
A neutral source? What the fuck do you think the literature referenced in Google Scholar was, a pro-animal cruelty labeling lobby? Is there such a thing? I don’t know what your game is here, but again, I really don’t care what you believe about animal cruelty. The fact is that it is well established as an indicator of significant antisocial behavior in numerous empirical works.
Relatedly, Frick’s work on callous unemotional behavior and Lynam’s work on childhood psychopathy show how these traits more generally are strong predictors of later aggression, violence and serious delinquency.
I don’t know what is going on for the specific child in the story. I’m only providing you with what this kind of behavior means in general in terms of the development and course of antisocial behavior. Like it or not, I really don’t care. I’m not interested in a debate on the matter.