So the John Does may end up including any major isps that block sitefinder for all of their customers.

I would find that very interesting. If an ISP, which is a private network, chooses to implement a blocking device for any IP address (the SiteFinder server) for their own customers they would have the right to do so. Heck, they block protocols and ports all the time, redirect URLs and use filters for spam, adult sites, etc. If the customers complained, it would then be in their best interests to change make adjustments, but they sure don't have to. OTOH, if the registry implements something that interferes with the ISPs current applications, they most certainly must do whatever is necessary to restore functionality. If the registry implements something that the ISPs can't remedy with work-arounds, I'd betcha they would turn around and sue Verisign just as quickly and be able to show losses and expenses to boot.

I would be fascinated to see a court rule against a private network owner on such an issue and wonder how the judges would react to receiving that much more spam as a result of filters not working any longer, or their email being lost in a black hole, or their actions tracked without having been able to opt-out prior to that tracking being done?

It would be a sad day, IMO, if a registry were able to force another business operation to kowtow to implementations that cause the ISP and its customers harm. Verisign's complaining that they are being caused harm is spurious, IMO, since what they consider to be innovation is, instead, harming so many others who are now doing what they can to route around the damage.