Well, it seems somewhat unfair to judge the decision on information not available for decision-maker, however, I fail to see how is that an ‘implicit premise’.
I didn’t think Geneva convention was that old, and, actually updating on it makes Immerwahr decision score worse, due to lower expected amount of saved lives (through lower chance of having chemical weapons used).
Hopefully, roleplaying this update made me understand that in some value systems it’s worth it. Most likely, E(\Delta victims to Haber’s war efforts) > 1.
A is not bad because torturing a person and then restoring their initial state has precisely same consequences as forging own memory of torturing a person and restoring their initial state.