I'm no Nietzsche expert, but something smells off here.

If slave morality is born of "the [idea that the] good is what is most useful for the whole community, not just the strong" - AND - if slave morality is also based "devaluing that which the master values and the slave does not have" - then I think we have a invalid argument.

You can't want what is good for everybody while at the same time devaluing what others cherish.

That only works if your definition of "good" is destruction. If so, then whoever wrote the wikipedia article is just out to confuse. I suspect Nietzsche is way too subtle for such nonsense.

I'm no Nietzsche expert, but something smells off here.

If slave morality is born of "the [idea that the] good is what is most useful for the whole community, not just the strong" - AND - if slave morality is also based "devaluing that which the master values and the slave does not have" - then I think we have a invalid argument.

You can't want is good for everybody while at the same time devaluing what others cherish.

That only works if your definition of "good" is destruction. If so, then whoever wrote the wikipedia article is just out to confuse. I suspect Nietzsche is way too subtle for such nonsense.