AidanBionicle1? I haven't heard that name for years...
For an indication of what behavior led to his being banned, I direct you to this topic, in which he actually asks why people disliked him and got answers. This is a ride, I tell you, beginning with a few members telling him why people have issues with him - he was rude and immature, and attempted to be explicit. and a few people called him out for swearing in a post. He insisted that because it was 'his' topic, he got to set the rules for that topic, before staff came and swiftly clarified that it was their site.
From what I gathered reading his response - which I'll include below to save a few people a click - he still bears a grudge against TTV, and he doesn't see apologizing for his immature actions as important as maintaining that grudge. The "I did X... but" clause implies to me that he still don't consider himself worthy of punishment. This isn't to say that TTV has been blameless, though, as we saw during the incident of Eljay's firing and subsequent revelations about Kahi.
As for how much he's changed... I can only hope that he has matured a lot since then. Seeing his old posts compared to how collected his response was in January, it certainly seems plausible. While I don't think he'll ever be allowed back on the message boards - not that he'd want to be, likely - I hope he's truly learned from his mistakes and finds success elsewhere.
Aidan's response -