Not true. There are two different things going on here.
About a year ago, I reported gas112 openly on the GD forum, for what I thought was a really bad post. About a day or so later, I noticed he was no longer posting. So, I checked the drop down search box to find when he last posted, and his name had gone missing from the search list. When he returned, his name was back in the search list. That is how I worked out that, when somebody is banned, their name goes missing from the search list.
Then there was the time, a few months later, that gas112 kept getting banned from all new threads on GD. He posted openly about that.
I don't know if one of these is the 'warning' you are referring to.
I actually like gas112 and I don't understand what he did to get a permanent ban from GD.