Doubtful since NAT is a service with multiple RFCs defining various methodologies for mapping. That is: software expects NATing. Software expects IPs, ports, etc. to get redirected. I guess if you wrote your own NAT service that did not conform to RFC standards, it might be considered a modification of the original intent, but I suspect the issue would have to be with changes to packet data rarther than the header… now try explaining that to a copyright judge – because I bet some will choose to not understand.