Comments of chapter undefined of DxD: I got Isekai’d In Ecchi girls World

I'm super confused on whats even going on anymore. Why would they try to kill him just because he's "mentally unstable" or showed sadistic tendencies in battles when basically all of rias's peerage has basically similar to worse backgrounds than what the mc showed. Like akeno in her eyes being abandoned by her father and watching her own relatives kill her mother and then she exhibits sadistic actions when facing an enemy where she purposefully tries to inflict as much pain as possible to them. Even though kiba went to do his own thing in the excalibur arc there must have been signs of his irrational hatred or something before and even then, since this precedent occurred if kiba because of his own mental instability acts up and strays away from the peerage for the excaliburs don't they gotta try and kill him off now? And if rias couldn't control a member like gasper and they sealed him off you saying they couldn't do other means to try and deal with this "issue" they have.