From what I've read, the defense was largely a matter of repeated insistence that there can be no real proof that a particular person or machine was involved because there are enough was to spoof the trace information.

The defendant was not using wi-fi. Is it that plausible that an outside person could engage in file sharing using a spoofed IP address and user name? Could someone go on a P2P network, look at who is online, and then clone someone's identity?