He didn't know that Li Chengyun had already taken note of him and decided to dismiss him from the residential area.
First, there were too many sympathizers who had no idea what had actually occurred and wanted to help Su Xin simply because she was a woman.
Second, and most importantly, the security guard showed no responsibility, demonstrating his fear by running away directly, abandoning Su Xin without attempting to properly deal with the situation.
Imagine if something had happened in the residential area while Yu Jingrong was still inside, and it just so happened to be the day this security guard was on duty—the consequences were too dreadful to contemplate.
Seeing that the security guard was so afraid of Li Chengyun that he ran away, Su Xin had actually wanted to run too, but she knew she couldn't; she still had to ask Yu Jingrong where her daughter Su Luo was.
