Your argument: we can’t possibly know everything, therefore assume nothing is correct. Except reality is a persistent illusion, so we work in that reality. Your fantasy world where there is a god that can see all futures is fantasy. Don’t confuse the imagination with reality.
Your philosophy is literally dependent on information that’s impossible to know which is a real limitation. In the real world we can estimate harms and benefits, but it’s the unknown factor which makes sacrificing someone ‘for the greater good’ so abhorrent.
If the rule is to minimize total probable harm, then you need to consider second order effects of choices. You further need to carefully consider/model repercussions rather than assuming each choice has obvious costs. Simply shooting infected people may reduce the risks of spreading a plague in the short term, but it’s got huge long term issues as people then try and hide their infection etc.
It seems like it was responsible for WWI, WWII, the Spanish flu, etc but would worse things happened instead? I doubt it, but maybe it indirectly prevented total nuclear war.
Which when you get down to it is true of everything, we need to act with imperfect information.