It has nothing to do with PC rules. The bestiary 1 had an entry for sneak attack in the ability glossary that specified the sneak attack application conditions that included the specifics for weapons (agile/finesse).
For example in Bestiary 1: Kobold Warrior uses a spear with is non-agile, but had sneak attack as an ability. One could argue that while they have the ability sneak attack that added a damage die, it wasn't using an agile weapon, so it did not trigger.
That's the situation I hope they clarify.