I suppose the ban length is a bit harsh, but it could also be right considering the history you have with Target/Revenge RDMing people. That shouldn't be the way you deal with RDMers. I'm not going to make you promise to stop Revenge/Target RDMing but, You should really reconsider calling in VIP's or Admins to the server rather than dealing it "your" way. Either way I suggest you give DP a shorter length ban. Perhaps make it 1 week rather than 3.
I wasn't the admin who banned him, nor was I on the server at the time of the ban, but I do agree with Lazord on some level.
The initial appeal was passive aggressive as fuck, but at the same time, you didn't outright start insulting people.
Speaking solely from my past experience with Dark, he's one of the smartest "regulars" on the TTT server. While at times, he can be pretty misguided, I do know he at least has good intentions at heart even though his approach isn't... always the best.
Anyways, if the choice was up to me, I'd reduce it to a week.
But it's not.
And chances are, Ruben is going to keep the length/deny the appeal.
Either way, I thought I'd just include my two cents.