A few decades ago, during a return flight from Caracas, the captain came down with a bad case of stomach problems and had to vacate the flight deck. I had a choice between a passenger who was also a board member (one of my big bosses) with a PPL and one of our engineers.
Long story short, I chose both. While Mr. board member was good with the radio and gee whiz conversation, my man in the overalls (not really) was like a seasoned member of a well-oiled team and was seated accordingly.
Even though a PPL holder has actual flying experience, an individual from your own team is almost always the best choice in rare cases like these.