Sentence meaning in a board game

Ok so this is a game where each player controlls an explorer, and at a certain time we have to choose a person to became the traitor.

The following is written:

"Oldest player (not necessarily the oldest explorer)"

In the sentence inside the () does this mean that we have to choose the oldest player (actual person) or we can choose the oldest explorer (in character)?

My doubt is because the sentence makes it (to me at least) seem like its an option not a manditory requirement so speaking in english terms only and ignoring the game rules does this mean we HAVE to pick the oldest player or its an option and we can pick the oldest explorer?

P.S the game is "betrayal at the house of the hill"

Solution 1:

The meaning is the oldest player, regardless of whether their explorer is the oldest or not.

The circumlocution is required because if the oldest player might be controlling the oldest explorer, so they couldn't absolutely eliminate the possibility that the person referred to is the one controlling the oldest explorer.