Um this was not a secret. They disabled you from doing the chestsaw-to-bomb when your opponent is in the air ONLY. I'm 99% sure this was in the NRS notes for the patch update. There isn't really a practical way to doing chestsaw-to-bomb if your opponent is just standing there. They'll just block, jump away, or teleport if able. You're better off doing this,
2,1,mid-bomb, down 3 poke for a quick startle and then they'll probably block, 2,1,2, that pushes them into the mid-bomb.
Or..
2,1,mid-bomb, down 3 poke, chestsaw (which pushes them into mid-bomb)