So it seems that not all named enemies always drop targeted loot. I happen again somehow to be searching for Murakami in Federal Triangle. By my count, three of ten drops (cases and non-named enemy drops) have contained targeted loot, which is perfectly in line with what's expected. But I've also done three non-daily, non-weekly bounties here (two normal and one hard difficulty) and not one of the three named targets of the bounties dropped targeted loot at death.