The law is only meant to apply to citizens of Utah though. Blocking all exit relays would mean that absolutely anyone accessing that website would not be able to do so from a VPN which burdens people outside of Utah too.

This is what I was missing. Demanding that porn sites block VPN traffic (or only accept residential traffic) would mean that everyone everywhere using a VPN gets blocked not just in Utah.

I still suspect there's some kind of solution. Like Utah could tell VPN providers that if they service a customer in Utah then the VPN provider can't route traffic to adult sites. Or put the burden on the VPN provider to do age verification if porn is gonna be available through the VPN.

Come to think of it, I'm still a bit confused as to why VPNs are even relevant because it would seem to me that age verification would be done through some kind of having-credit-card type scheme which VPNs are entirely irrelevant to. I even read the article and I'm still confused. Oh well.