That does beg the question of what defines what is and is not an action, though. Is it only things that are defined within the types of Actions? Only things that require some sort of motion or conscious choice to act?
If it is based on the types of Actions, does that mean that Defense becomes an action when you use an Interrupt like Block or Parry?
In that last case, it seems odd that some "action" bonuses would only apply to some defense tests but not all...