From a female's perspective, maybe your original PH and his wife made the decision to not announce the pregnancy to the whole world until closer to the due date? Furthering the inconvenience for everyone involved, but I can see the reasoning. I would be upset if I had specifically requested someone, and then "accidentally" found out about the change.
However, having hunted with a young PH on our trip to Africa, don't count them out. Ours was very driven, and had the knowledge of someone much older, and was truly a class act.