Here's the entire abstract of the study Peterson linked. The study divides men into three groups. One is at high risk of violence, "Sexually active men, who are not in a monogamous relationship." Two are at low risk of violence, "men who are sexually active within monogamous relationships and men who are not sexually active." Peterson's claims were about violent attacks and particularly the 2018 Toronto van mass murder. The perpetrator was a 25-year-old male college student. He was never married. He has stated that he never had a girlfriend and was a virgin. He described himself as an incel. Evidence places him in the category "men who are not sexually active." That's a group identified at low risk of violence! "Fewer partners since last wave" is pretty different from socially promoted monogamy, let alone from marriage. "Results were not accounted for by marital status." Looks like a lazy five-second Google by Peterson that gives little if any support to his priors.