Actually they did do human sacrifice:
"One issue that intrigued me was based on intimations from some authors that human sacrifice did not exist in ancient Egypt.
[5] Egyptologists largely denied the existence of the practice, sometimes with vehemence.
[6] I had always accepted this line of thought, until a fellow Latter-day Saint in my doctoral program, Val Sederholm, pointed out one possible instance of human sacrifice in Egyptian history.
[7] Neither of us felt that proof of human sacrifice in Egypt was necessary for the support of the Book of Abraham’s story about Abraham’s near sacrifice since Abraham made it clear that the priest who nearly sacrificed him represented an amalgamation of ancient Near Eastern religions (see Abraham 1:7). Some of the cultures represented certainly performed human sacrifice. Still, the whole concept of sacred violence fascinated me, so I set out to write my dissertation on the religious framework for sanctioned killing in ancient Egypt.
[8] I did not have a particular axe to grind; I merely wanted to discover what had happened in Egypt regarding this matter.
For a year and a half, I dedicated almost all of my time—sometimes fourteen hours a day—to researching and writing about sacred violence in Egypt. What surprised me most was how well the Egyptian culture I was discovering matched the culture painted by the Book of Abraham, and also how this knowledge helped me to understand various nuances of that book. Here I can give only the briefest synopsis of my findings."
More at:
Egyptian Papyri and the Book of Abraham | Religious Studies Center