[rimiform]

The person you're disagreeing with agrees with this idea about morality: (https://en.wikipedia.org/wiki/Person-affecting_view). You, on the other hand, (I think) believe something can be bad even if it is not actually bad for anyone.

Case in point: the people who've actually died in said genocide cannot have any feelings about what we do about them, so to consider those feelings would be nonsense (according to the person-affecting view).

Of course, if someone living (such as yourself) cares about this, then it would still make sense to care about it, since the feelings of an actually living person are concerned.