Earlier quoted context omitted.
If I told you I put a chemical into the water supply that gave people brown hair you’d probably think I am weird and stupid but not evil. If I told you the chemical gave people down syndrome you’d probably think I am evil. Whenever these topics come up there’s always people saying things like “but what if people like it?” And I can’t help but wonder, really? Are we really having this conversation? The answers are obv…
If you force something major and permanent on somebody without their consent for no good reason, of course it would be evil. It would be evil to force somebody gay to be straight and it would be evil to force somebody straight to be gay, that has nothing to do with the goodness or badness of being straight or gay. Hair dye is temporary.
If doctors gave mothers a vaccine that prevented down syndrome, at a high level, that would be the same as putting an anti-down syndrome drug in the water supply.
The point of the example is not about whether putting things in the water supply is good or bad.