TheWholeLoaf is correct, your friend should be the one posting his own appeal.
I will save both of you the effort though: the perm ban was no glitch. Your friend joejoe was banned 3 times by our anti-grief system; twice by the same trap and once by a second trap. These traps automatically give out 7 day bans.
I looked up your friend's ban history when I found grief he'd done to another member's build, over 100 blocks were ripped off of it. This shows a complete lack of respect for others builds, and a complete refusal to play by the rules despite three prior week-long bans.
I also find it unlikely that your friend's account was being used by someone else. I am denying and locking this appeal. If your friend feels that he has some better evidence to bring to an appeal, than I welcome him to create his own. But it would have to be very good evidence.