Update: one thing has been bugging my mind: if he truely did this by accident, and his first reaction was that someone is framing him, that means he thinks he really typed that text. This is weird, how can he not remember he didn't type those 80 words, just 10 days later?

People should really make sure they're quoting people properly in the first place though, but I fail to see how this was a misquote. If it was surely there would be some original material in there?

I suspect this user just used that as a desperate excuse to try get out of the ban, but is this just a one off? Usually copy and pasters don't just do the one and have copied multiple posts and make a habit of it. When I used to search for them and I found one I'd try find another because if you find two or three cases then they don't really have a leg to stand on and if you can find another or more examples then this excuse would become less believable.