The problem is that I had never seen this before - to my knowledge it has never occurred before. The 50% rule has appeared only in the latter part of my time here and not everyone has used it since it was first proposed. In games it has been used I am not aware of a situation where there were insufficient valid targets in this manner. It never occurred to me - or indeed, anyone - that such a situation would arise. If it had I would have explicitly stated the situation. When it did eventuate it seemed intuitive to me that the answer was that without a valid target and you cannot redirect the lynch. Unfortunately it was only when I elucidated it I realized that if you'd known this you'd have avoided the situation. If I had realized you interpreted the rules differently - which is not unreasonable because they say nothing about the situation - then I suppose I would have leaderlynched Paendrag on the basis that with proper information you'd have put yourself ahead in order to free up a valid candidate.
I am very sorry for this outcome. You have a right to be frustrated by the outcome: I correctly observed the rules, but I had failed to make the rules clear to you, and that's always a bitter pill. I can only apologize; it should be clear from our private correspondence that I was willing to give you every opportunity to use your leaderlynch. In future I suppose the 50% leaderlynch rule needs to explicitly state that in the event of a tie the leader must have enough valid targets to account for all lynches, so that if 2 people are tied, 2 people must be lynched, even if 1 victim is not changed.