Stupid idea is stupid. First of all physical damage to destroy data on a hard drive is a horrible way to go about things unless you plan to entirely melt it or grind it into dust particles. Why not just encrypt it and cut power? More realistic, and far more effective, and no destruction of evidence charges. Maybe contempt of court if you refuse to give up the password, but that is what deniable encryption is for. As far as Tor goes of course it can be hacked, just in the past 12 months there have been several remote code execution vulnerabilities in it. Pretty much nothing should be considered hack proof unless it has been formally verified.