Note that the Chicago police chief he chides for focusing on guns made his career as NYC police brass. He was brought to Chicago to bring NYC-type policing to town, including the famous...or infamous...CompStat. See Second City Cop for one cop's opinion on Compstat and McCarthy.
He (Lowry) is, of course, dead on target. I think it has long been known that in any city it is a relatively small percentage of the city that shares dysfunctional culture that is responsible for most serious crime. But in those same cities it is a no-no to focus on this; so much easier to blame the NRA.
I think I would argue with the assertion that it is the "social conditions" that cause people to be violent gang criminals unless you count cultural characteristics as "social conditions". If that were the case, then providing money, building housing, and making loans easy to obtain should turn this around. But of course it doesn't. It is the constant cultural emphasis on victimization, blaming other parts of society for one's own problems, and allowing people to excuse themselves for bad behavior because somehow others are responsible for it, denigrating the very things that lets other parts of society move ahead, that creates a self-defeating society. There are lots of poor areas and poor societies, but they don't all go gang-banger.
I wish he had linked to the study he mentioned, the one by Andrew Papachristos. I shall have to go googling.