Is it purely because of a promise made to the Primordial Divine Ape?
Not to mention whether he could even obtain the power of the Desolate Venerable, even if he were lucky enough to acquire it, he certainly wouldn't just hand it over to the Primordial Divine Ape.
"If you can help me lock onto the Desolate Venerable inheritance, I can promise that we will split it down the middle."
Chapter 1264