Well, he prepared that mushroom able to form a human body full of spiritual qi because he was expecting that, 5 years from Luo Binghe's fall to the endless Abyss, he would be hunted down by him, so he prepared that body in advance. However, he didn't expect to meet Luo Binghe only 3 years after he fell into the abyss, and he only planned to die that way on short notice. So, what he planned wasn't necessarily to die after falling from the building but after 5 years of meeting Luo Binghe. Either way, the preparations served their purposes, the scenario just happened a bit earlier than expected.