You obviously haven't seen the fight. If you had, you would know Johnny Lewis stopped it. There was even speculation afterward that Tszyu had sacked Lewis because he stopped it. The fight is still on Youtube.
Serge is always the best and most unbiased on the forum. If you can't trust Serge, you can't trust anyone!
Based on feedback from their fighter, who had already mentally quit. Champions are usually too proud to openly quit. A good corner will discern their fighter's body language and make the right judgment. Tsyzu did not want to go out for round 12, so his corner stopped it. Then Tsyzu quit the sport, rather than fight Hatton again. That's two TKO losses at his best weight that he did not try to avenge, and his overall resume isn't impressive enough to skim over these unfulfilled rematches. I am not sure why he is so romanticized here.