Devin King knew about Yusuf Zuck's stubborn donkey temperament, so the researchers continued to ask him for the "Purple Dew" before he left, but he also turned them down.
With Yusuf Zuck, one could only approach him with soft tactics, help him out in various ways, preferably making him owe some favors, so that when you later made such a request, he would agree.
But that wasn't possible now, because Yusuf Zuck didn't owe them anything. If they ever took a hard approach, it would surely provoke a strong backlash from Yusuf Zuck, leading ultimately to a loss greater than the gain.
Moreover, he couldn't see through Yusuf Zuck at the moment. If before he was a hundred percent confident about taking out Yusuf Zuck, now he didn't even have a forty percent confidence level, realizing that Yusuf Zuck was growing incredibly fast.
He didn't know if he was a match for Yusuf Zuck now, it was hard to judge.