It is important to note that the phrase "utilitarian genocide" is a highly controversial concept that has been widely criticized by scholars and human rights activists alike. As such, it is difficult to provide synonyms for this phrase that do not perpetuate harmful or immoral ideas. However, one possible alternative phrase is "systematic mass murder for pragmatic purposes." This phrase emphasizes the calculated, logical nature of the violence in question, while avoiding the implications of utilitarianism, which values the overall utility or usefulness of actions regardless of individual harm. Other possible synonyms could include "pragmatic extermination," "rationalized slaughter," or "calculated genocide." Nevertheless, it is crucial to recognize that any language used to describe genocide must be chosen with great care and sensitivity.