Diana's words made her stance clear: I will protect this world!
They could also be understood as: Yinsen, don't come steal my job!
Aside from nodding to say there was no problem, Yinsen could not possibly give any other answer. Besides, he felt that leaving Diana a few "villains" would give her something to strive toward... and help pass the time.
If he really wiped out all her enemies, what else would Diana do? Return to the divine kingdom with him right away, build a palace, live in that cold and lonely place, and then, with nothing else to do, find her own amusement? Like bullying Ada and Selene, or picking fights with Yinsen whenever she felt like it?
That would not benefit their relationship at all. Whether men or women, adults or children, as long as they had something to do, the chances of causing trouble dropped considerably. Of course Yinsen understood that, so once Diana said she had something she wanted to do, he would never object.
Likewise, Ada liked going to certain worlds to "grind through dungeons," and he would not stop her. He would even "assign her missions" to make her dungeon runs more enjoyable.
When everyone had their own things to keep them busy, they would not spend every day gathered together, getting sick of the sight of one another and starting a war. That was also an important reason why Yinsen had been living so comfortably.
Now that Diana had a goal, she devoted herself wholeheartedly to improving her strength and striving for the Higher Realm. When she casually waved Yinsen off and said, "Nothing else? You can go now," Yinsen felt a little depressed.
"We still haven't discussed the divine kingdom."
"That sort of thing isn't urgent. Until Darkseid is completely eliminated and