OK, but now decreasing your margin of error until you can make a determination is the most important ethical mission in history. Governments should spend billions of dollars to assemble to brightest teams to calculate which of your two options is better -- more lives hang in the balance (on expectation) than would ever live if we colonized the universe with people the size of atoms.

Suppose a trustworthy Omega tells you "This is a once in a lifetime opportunity. I'm going to cure all residence of country from all diseases in benevolent way (no ironic or evil catches). I'll leave the country up to you. Give me $5 and the country will be Zimbabwe, or give me nothing and the country will be Tanzania. I'll give you a couple of minutes to come up with a decision." You would not think to yourself "Well, I'm not sure which is bigger. My estimates don't differ by more than my margin of error, so I might as well save the $5 and go with Tanzania". At least I hope that's not how you'd make the decision.