I think Delun and Yichen are two sides of the same coin tbh. They both want the PoMA world to be independent and not be gangraped by all the outside cultivators and Immortals, but where Yichen wants to do it on hard-mode (relying on old methods, IE, and Ruo), Delun wants to do it new style (relying on making everyone in his army a cultivator, leveraging Qi and Dao knowledge, and utilizing the MCs extreme talent to its maximum).
In the new update it was revealed that Delun forbade the Wu Heir's cousing from becoming a disciple of LB even though it wouldn't make sense if he were just a LB fanboy. That, along with the fact that he made that Karmic Shield for the MC and did his utmost to make the MC an independent being as opposed to being TW reborn, leads me to believe that he's trying to maximize his profits and prep by utilizing the cultivator knowledge, but he definitely doesn't want to become a vassal and/or slave to LB, Yue's, or any number of other cultivators.
The core of the issue I think is once again what Yichen is hiding in regards to the Ancestral Blood Droplet, and all the other goodies he has leftover from TW. That's why he's a fool in the eyes of Yichen but not a direct 'enemy' so to speak - they have the same goals but Delun is playing a way more risky but potentially more profitable game.
That's why I think the MC's mom also strictly was against allying with him, I think he's willing to do everything to accomplish his goals, and that's why he wanted the MC from childhood so badly - to mold them into his own personal weapon/protector of the realm, without regard to the MCs wants. And to be honest, if we were to grow up with Delun, we would've been way more powerful and started cultivating way earlier since he already knew about all the Qi and War stuff.
That's disregarding even more mindraping ofc.