Hopefully that kind of thing is worked out before someone is chosen for a mission and is issued the poison with everyone thinking that everything is in place.
In ground units where that might be called for, you can hope for a friend to do it to you before they have to move on.
Who knows.
Post 33 raises the fact FGP was not explicitly told to (or expected to) kill himself.
The pill would be an option, not a requirement.