He was just a kid when he pulled the whole I AM OGIS!!!! business. And hardly anyone still active in fantasyland was even a member at the time.
Besides, if I recall correctly, the account he had just prior to Tyrion immediately admitted to being Ogis and asked to be unbanned on the basis of his improved behavior. The mods rebanned him without even considering it.
This is why permabans are generally a bad idea unless we're dealing with the likes of Kyle Mercado or Robert Stark.
Well, they actually supposedly considered it, and let me be a member of the forum for more than a year. Then I went inactive, came back, and found myself banned, despite my identity being advertised in my username the whole time. Presumably, it had something to do with Dave mostly ceding forum duties to Nym. I have no idea.