Although im sure my opinion won't matter much since i am a friend of the accused, i would just like to say that this really was a one off situation. I have played with Rennie for years throughout multiple Gmod servers and have never once seen him hacking, hence why i was so surprised when i found out he had ESP.
After having the situation explained to me that he just forgot to toggle it off whilst afk in spawn, i was honestly shocked since i had no previous knowledge of the ESP.
However, i have played with rennie the last couple days before he got banned and it has been very clear that the citizen hack has not been activated or used for the majority of the PVP that Rennie partakes in. As stated by himself, rennie only recieved a handful of kills with this hack and i feel as if the quick reaction of Phoon, gathering the evidence and banning him accordingly has dissuaded Rennie from ever attempting to use any cheats on CSI servers ever again.
I am going to give my friend a +1 on his ban appeal and hope to see a reformed Rennie once again on CSI servers! :)
Much love, Captain