Mao didn't want to kill Deng.
Mao had many opportunities to kill Deng, but Mao never did. Dang is confined, has no freedom, but his living conditions are not bad. He was not beaten and tortured like many others.
That's why Mao is a genius. He knew well that China was incapable of fighting the Soviet Union at that time, so he planned to attack the Soviet Union without causing a major war between the two nations. The plan to attack Dasmanky was a genius idea, a small conflict that sent a powerful message to the Soviet Union.
Politics is war without bloodshed