My (somewhat oblique) question is why copyright would apply to a dead guy's works. ...It's not like respecting copyright is going to get him to write more.

The standard answer is that it incentivizes living authors to know that their heirs will be able to continue to benefit from their work.

In any case, the question of why it is that way doesn't much matter for this particular question. Regardless of why copyright applies to a dead guy's works, it does.

IANAL

That may depend on whether they are John Paul II's notes (and the Bishop of Ombi's etc.) or Karol Wojtyla's. And whether the published work belongs to The Church or to Dziwisz.