I guess look at it from the "businessman" perspective. You start advertising a modern-ish war game set for release a month from now when a real and highly publicized war is going on, it'd be a PR nightmare (plus as I pointed out it really does not help a major plot point in AW1 is an alternate universe version of the Russian military invades a neighboring nation, way too eerily similar to what's happening now).
Also from a businessman perspective: it's probably best they delayed it anyway because IMO it was weird they were releasing it only two weeks after Kirby (which is still on track for March 25 as I imagine a whimsical platformer is far more the kind of escapism Nintendo would rather release right now, even if the setting looks post-apocalyptic, though not in the "destroyed by war" sense, more in the "the inhabitants mysteriously left one day" sense).