Yay for VPN!
Won't help you if you are misidentified as a DMCA violator. What if someone clones the MAC address of your cable modem or Comcast does not get their dates straight and you are assigned an IP address used by a pirate.
what makes you think they can legally inspect anything done inside a VPN?
Not just legally...assuming your vpn is encrypted, there is no way for them to decrypt it. That's the whole point.