The real-world error bars are quite wide because of the impact of moral character on a person's value, but sight unseen I would give the last seat in the life boat to the non-mentally-disabled person almost every time, yes.

Am pro-abortion in extreme cases involving rape or abuse

See, now that's a viewpoint I don't understand at all. The question of whether or not killing a fetus is killing a person is not affected by the circumstances of that fetus's creation.