What did General MacArthur and the U.S. government consider so valuable that they were willing to pardon the members of Japan's Unit 731 during WW2?

by strongerthenbefore20

Unit 731 Wiki-Warning, contains graphic descriptions of the Unit's crimes. Not for the faint of heart.
When I first read the history of Unit 731, what shocked and disturbed me almost as much as the Unit's horrible actions was that General MacArthur and the U.S. government pardoned the members of Unit 731 despite the horrendous atrocities they committed.
The main reason the Unit 731 members were pardoned was the U.S. did not want any other country to get its hands on the data and results of the Unit's biological experiments, as well as the fact that the U.S. knew that they would never be able to get the results from conducting their own experiments, as the Japanese were only able to get their data from performing lethal experiments on thousands of prisoners they took during the war.
But from what I have researched, the results of Unit 731's experiments were neither groundbreaking nor even practical for most purposes.

So what exactly did the U.S. consider to be so valuable that they were willing to let these monsters go unpunished?
Was the U.S. aware of the full extent and nature of the Unit's crimes when they pardoned them?
Although this idea may come across as pretty dark, I feel that in this case, it is fully deserved, and that idea is that the U.S. would tell the Unit 731 members they would pardon them, and once they got the data, they would just execute them after. Why didn't they do this?