Except that there’s no certainty that this is God’s warning, since this is a private revelation that hasn’t been approved by the Church.
Where has the Church declared otherwise? In what forum has the Church taught that Catholics ought to have a 3 days of darkness survival kit in their homes? Where has the Church put conditions on the mercy we’re to extend to the suffering? Why aren’t priests, bishops and even the Pope speaking, writing and preaching publically about this? Don’t you think this would at least concern them somewhat that there are possibly hundreds of millions of unprepared Catholics who would die as a result of not knowing what to do in this situation?
It doesn’t matter how many times you compare this to what happened in the Old Testament. This is nothing at all like what happened to those who mocked Noah, or what happened to Lot’s wife. This is a private revelation that supposedly occured after the close of public revelation, that isn’t contained in any approved apparitions, that hasn’t been the subject of any mass attempt by the bishops, priests and popes to educate Catholics of their peril and instructs Catholics to disobey the Biblical commandment to extend mercy to the suffering.
It doesn’t wash.