Simple. You can't just die and lose the tadpole because you and your parry are special. It's said multiple times. Your tadpole is different. Notice no other True Souls are running around using the same super powers, and the Absolute REALLY wants you.
I think that's the default answer, yes. Or if we really want to hand-wave it away, there's this:
The tadpoles allow party members to see through the eyes and link the minds of other party members, right? That's already established. So the tadpoles know in advance whether their host is likely to be resurrected in short order, and they hang around for it. That doesn't happen with other True Souls that don't have the same strong bond of our adventuring party, and the foreknowledge of what will happen after death of the host.
Yeah I know, that's a stretch...
