No, you can't do that. That said, there is absolutely nothing from preventing you from creating a parallel DNS infrastructure which copies the part of DNS you like, and doesn't copy the part you don't like. Running a root server is not a whole lot different (except in scale) than running a regular DNS server. Distribute your own root cache to your 'clients' put a copy of the root servers for the domains you care about into your machines and recursively resolve the rest with the regular system.
At one time this would have been prohibitively expensive but with Amazon's EC-2 service you could run a separate namespace for about a million customers easily for $600/month maybe less.