Polysemy of ought.
To some, “X is bad” means “after all ethical calculations are complete, the existence of X is a net negative”.
To some, “X is bad” means “when doing our ethical calculations, the existence of X contributes a negative term”.
Under the second reading, immediately removing X might still be harmful, because the map from possible worlds to ethical valuations isn’t continuous. Nearby worlds do not necessarily have nearby ethical valuations. The nearest world which lacks X may in fact be worse than our world for various reasons, even if X itself is contributing negatively to our world-valuation.
Much confusion has arisen from this.