If you read his entire wiki there are just a stunning number of red flags (the whole thing even, not just the controversies section). In this HN thread alone people have casually pointed out some obvious flaws. At the very least he's putting a lot of effort into spreading FUD about violent crime.
I really don't see how you can take him as a useful and objective source on these issues unless you're already coming to the conversation with some kind of anti-urban prejudice.
In some ways it reminds me of the conversation about child rapists and pedophiles. People lose their mind over the safety of their children when exposed to the community while ignoring that most of these crimes happen within their own families. It all just smells of a general fear of the vague and dangerous "other."
His research was one of the reasons I moved my family to the suburbs where violent crimes are excessively rare and committed predominantly by visitors from the urban centers.