It doesn't really make any sense. I've already shown the damage that bad laws do to create violence. Drug prohibition, the criminalization of sex work, etc. - the people involved in these industries drive and are victimized by most of the violence left in our society. About the only violence left is sexual violence, and even this has declined massively in the past twenty years, thanks to cultural shifts - in large part driven by better laws and practices, like making rape kits available, going after rape culture, etc.
In other words, Spiders hypothesis is bullshit. There is literally no way to look at the advances we've made while also factoring in the root of the remaining violence and come to his conclusion. It is nothing more than ideologically-driven nonsense meant to justify inertia.