Yeah...it is intended that the event could fire for a dead father...in fact there area a variety of events in this deries that will do so. In part I wanted to give the player some notification that a change had occured (since it can affect your inheritance, etc.) and also in some cases it is the only way (at the moment) to target a brother or sister. It's a little odd, I confess, but for flavour event purposes I can't put too high a priority on the coding of new targets like "best_brother", "random_brother", "worst_brother", "best_sibling", "random_sibling" or "worst_sibling".
Mnoracle: good catches. Those will be fixed for the next beta patch.