 This is the exportation principle. It is disastrous for any theory of impossible worlds. It implies that an inconsistency at some impossible world will spill over into an overt inconsistency. A true contradiction at some \(w\) implies that there are true contradictions, full stop. This is hard to swallow, unless one is a dialetheist. (And even  dialethists  may want to reject the exportation principle for impossible worlds: see Jago 2013b.)