I was banned a few years ago. My previous nation had an 80 percent warn and my next nation racked up a 60 percent warn. It was quite the surprise to me when the warns got merged and off with my head!
I rolled this nation and a member of the community, nice fellow, encouraged me to make an appeal to the GM team. I stated my case and one of them contacted me directly and told me I'm on double secret warn/triple secret probation so to speak. I earned off my warns and haven't had many problems since.
Getting unbanned is possible, just not for all, and I think that even if there was a general amnesty policy, there still needs to be an at the discretion of the Mod clause that they can invoke for particularly disgusting sorts of individuals. Other than that, I don't pay too much attention to all the moaning about the mods, seems like everyone complains about the mods in every game there is.
Such is the way of things.