Firstly, there isn't "a crime rate". You can't aggregate "a crime rate" across all crimes. Different crimes have different rates - you can't fold a murder into a rape into an assault into a burglary into a failure to pay a debt. If you think that there is "a crime rate aggregated over all crimes", then there's some fundamental things you don't know about criminology.
The thing about murder is that it's fairly unambiguous and usually recorded. Just about every other crime has interpretations and wild variations in recording - it's hard to compare across similar culture countries, let alone across time, without voicing an armload of caveats.
One example is comparing the assault rates in Australia versus that in the US. Australia has a much higher assault rate... until you look at the details. An assault in Australia carries several charges, the most severe of which sticks, but each of those charges makes it into the total stats. In the US, the stats are only published on aggravated assaults - those with a weapon or serious bodily harm. Two guys having a fistfight outside a bar will add to the Australian stats, but not the US stats. It's the same story with the same country across time - not to mention wildly different reporting rates, especially when you're considering a period where modern policing was still in its infancy. Murder is one of the most consistently defined and reportable crimes, hence why I used it.
was a major part of the reason why crime rates were so low.
That is very much putting the cart before the horse. Victorian England was rife with theft, unsurprising for a place with plenty of poverty and no welfare. I'd buy a 50-times increase in drug crime, because that's a crime now more than it was then. I wouldn't buy a 50-times increase in debtors crimes, because debtors prisons are no longer a thing and bankruptcy is no longer a crime. It's just hard for anyone with any familiarity with Victorian England to see it as 50 times safer than modern day England - this was a tumultuous time, with the industrial revolution obsoleting jobs left, right, and center. There was huge amounts of poverty, and there was legal reform at the time because the rise in petty crime against harsh penalties meant that there was a lot of dissatisfaction from the disproportionate response at the bench. There were huge problems with alcoholism (gin being very cheap) amongst the urban poor causing fights.
So, in context, is it safer to walk around Victorian England than modern-day? Well, the assault rate would have to be astonishingly low, because theft certainly wasn't, and we've already seen that murder was equal to or greater than today's rate.
Do you have a link to Moldbug's comment where he discusses this 50-fold decrease? I tried to find it as I wanted to see how it was sourced, but there's a lot of waffle - the front page is only two posts (and one announcement) that total 20k words. I have no idea where in the archives it might be.