Yea they all know he wants to act like a good kid so if she frames him by making others believe that he is killing them to hide the evidence of something which could affect his reputation, it will definitely work since they know he is capable of doing so
They worship him too much for that to work Rim Myaz
But they also fear him so much at the same time. One glare from him makes the twintails and delinquent dude stop fighting IMMEDIATELY. So I feel like the possibility of him killing his "friends" aren't too far off of an idea in their heads.
The Mc should use strategy like making them think the main antagonist is the one who is killing them one by one .