That was one fight, one night. Duran came back and done many great things after that. You need to look at his whole career, not just one fight. It somewhat harms his career, but surely that one surrender isn't the be all and end all.
I'm not saying that I discredit his whole career because of it, just that it might keep him out of the top 10. If he's somewhere 10-15 it still means he's a great, great fighter. But when you'r talking about the best 10 fighters that ever lived you have to ask yourself if that behaviour shouldn't disqualify you from that extremely elevated company. I mean he was an experienced fighter in a very important fight and he loses it like that... Sure, I wouldn't demote Robinson from nr. 1 to 11 because of one such episode, but it does cost a couple of places and that's why it might mean that Duran loses out on the top 10.