Well, as ever, that depends on which Cheetah you're talking about. Perez!Cheetah or Jimenez!Minerva would probably have found rape outright pathetic and child-killing merely distasteful. She was basically indifferent to the murder of adults (she did it herself often enough). WML!Cheetah and Byrne!Cheetah would probably have been equally disgusted by both (though again, both still fairly mellow about the killing of adults). Society!Cheetah wouldn't have given a shit about any of it, and Pfeifer!Cheetah would have liked Arthur more for both.
That PantsOfStupidity!Cheetah would react worst to the rapist bit does follow reasonably enough, IMO; between her powers and original personality and her subsequent experiences as the White Magician's prisoner, Ballesteros' and Circe's victim, and Diana's intermittent ally, a strong loathing for crimes of personal violation moreso than any variety of killing makes perfect sense.