The entire reasoning behind denying them the cure was based on a combination of subtle racism, gaiaistic nonsense (in which nature is personified, so that instead of random happenstances, it's regarded as having a "will" or a "goal") and second guessing or thinking they can predict the future course of evolution.
News flash: It's not the place of people to second guess the future. That way lies madness where nobody helps anybody. "Hey there's a guy drowning, I could help him but he might turn out to be the next Hitler, guess I won't save him then".
(As a matter of fact this did happen - when Adolf Hitler was 4 he fell through thin ice on a river in Austria and nearly died, another kid heard his screams and pulled him out. But there is no shame on that kid for rescuing him - even though Adolf went on to become who he became, it wasn't for that kid to know, and in rescuing him, he did the right thing.)