Magic Emperor - Chapter 784

MC kneeling down cements the fact that author knows how to add layers of depth to a character without giving a huge word salad. MC’s whole attitude towards most of other characters comes from him being Demon Emperor previously so the mortal realm is nothing in his eyes but a stepping-stone.

So far Zhuo Fan shown to have one core goal at a time while working on getting stronger for his revenge. From protecting his own (Luo clan Steward) –> using Demon Scheming sect to be stronger –> safety of his love interest given her unique physique. He will kill, lie, cheat, manipulate, it doesn’t matter if even the world burns, to reach his goals.

Right now, his high priority is to get his lady to a complete safe place ASAP, and Demon Scheming sect is far from it, even if he becomes its sect leader given his own cultivation isn’t as high to crush anyone coming his way. Thus, he is refusing one favor this old dude is asking despite owning old dude so many favors in return for being a massive guiding hand while MC has been at the sect. He can easily come back later, especially after his ascension to higher realm & repay all the favors tenfold.

But the moment MC realizes that the old guy handed him a knowledge/art so unparalleled that nothing even higher realm compares to it, he has no choice but to give in & kneel down in return because weight of favors he owes is that big.

In short, the game recognizes the big game when they see one.

Apologize for a wall of text, but this is my understanding on the moment.