Despite handling the execution list himself, knowing its contents very well, this was under certain conditions.
Secret executions!
Even other prisoners had to be avoided, only sneaking kills was allowed, to fabricate suitable reasons for executing these mixed-blood Titans in front of a large audience.
The more he killed, the more miserable he would be afterward.
The other side didn't care about this; being imprisoned like dogs for many years, the volcanic rage was not something that could easily be quelled.
Facing the aggressive mixed-blood Titans, the Prison Warden suffered a beatdown that was painful beyond words, but only skin-deep, with no actual threat to his life.
Continuously comforting himself to hold back, not to counterattack.
This was inherently a contradictory and abnormal relationship; with many onlookers, the mixed-bloods had their parents as their backing, while alone, they became ghosts claiming lives.