Cliff; I think that if the person had the intelligence and knowledge to be able to vary his/her IP address, then they possibly would have little desire to post such juvenile material. By the way, I believe that although the majority of PCs will get their IP address from a DHCP server (often incorporated within their own router), the external IP will usually be static, so it's easy to track. The offender would have to (say) swap ISPs so that a new IP address was being used.
Anyway, really glad that the Moderator can now take sensible action against those whose only aim is to offend and disrupt others.
John