Punkbuster hasn't supported COD2 for a few years now, so nobody runs it on their servers.
I wouldn't worry about it too much. Whenever somebody new shows up that plays too well we all watch them very carefully. Yes GUID's and even IP addresses can change, but a playing style rarely does and I've banned quite a few people that have come back in with all new information. We have a great group of admins and hackers don't last long on our servers.
By the way, I used to play IAF a lot when our servers were not busy, and while I really enjoy their maps and mods they get quite a few hackers and their admins are very slow to ban people. I even created a profile on their web site to report people that we had previously banned and were now playing on their server with the same name and still hacking. Most of the time no action was ever taken by them.