> In the same way it's proper to use same concept as a metaphor

Use as a metaphor depends on similar perception of the resonant features of the literal use since it relies on those carrying over to the nonliteral use; it is eminently clear that within our society there is not a common share perception of those salient features, so it is not a particularly good metaphor outside of narrow homogenous subcultures, and what it is a good metaphor for within each of those subcultures will be wildly different.

Metaphor is inherently highly culture-dependent.

By this logic, you think that something has to actually occur first before one can be morally opposed to it? I would have to first witness a genocide before I can have moral opposition to it?

Of course concepts can have moral weight. To suggest otherwise is foolish.