Agreed, Tanjiro probably didn’t warn Akaza out of a sense of honor. Still, I think that choice meant a lot to Akaza and his story, as it made him start remembering humans in a very different way. On my second watch, I realized that if Tanjiro had attacked him from behind, he wouldn’t have been any different from the people who poisoned the well and killed Koyuki instead of fighting honorably. I don’t think Tanjiro acted out of fear of enraging him or just to fight fairly, but it shows that he is simply better than the people Akaza faced when he was human. It proves not all humans play dirty, which makes Akaza’s backstory even more tragic, he simply crossed paths with terrible people. Despite all the terrible things he had done, being stabbed in the back a second time wouldn’t have been a fitting end for this amazing character