Quakerism is still a form of Christian faith. And for a Christian the life on Earth is but a small episode of existence. The point is to obtain the life eternal, the salvation. To suffer and be put to death for the refusal to reject the principles of the faith, aka martyrdom, is a known way to practically guarantee a salvation.

Of course, from a game-theoretic perspective, such ideas can only persist if someone else protects the pacifists from being killed, likely by use of lethal force. In this situation the only morally acceptable choice for the pacifists is to not be afraid of death, and not demand somebody to do the dirty work for them. Which is what we see.