I would look at the optional survivor benefit, which, as you pointed out, is something that is not offered by most pension plans. It is something that the public sector plans put in place—I think it was in 1992—as an option.
I would look at this like term life insurance. It's an option that is provided to members that allows them to provide for a spouse who otherwise wouldn't qualify under a normal pension survivor benefit. It's true that the member's surviving spouse will not benefit from that in all cases. It's possible that they will pay in for a benefit and take a reduction for a period of time and they won't yield the benefit of it.
Yes, the plan would not be paying out in those circumstances, and the funds would remain in the plan.