I think Initiative/Reticence do specifically help when defining the Story Goal, and are tangibly different from Pursuit/Avoid. The latter rely on the Story Goal to come first in order to align them, but I think Iniative/Reticence can be used in actually defining the Story Goal.
For example, take The Princess Bride. If the First Driver of that story (inner story) created some imbalance between Guilder and Florin, so that the way to take Initiative and deal with it was to start a much-needed war, then the Goal could indeed have been to start the war, and Humperdinck could have been Protagonist, Pursuing such a war.
Instead, the First Driver is the combination of Westley's ship sinking and Buttercup getting engaged to the prince, setting up the inequity of that engagement (part of the scheme to murder her and start a war). Once that inequity is established by the First Driver, reticence is to let it play its course (Humpderinck's side). While initiative is the drive to stop the scheme and save Buttercup -- and that's the Story Goal.
Notice that at face value it seems like Avoid (avoiding the war) more aptly defines Westley & Buttercup's drive, which is why reticence and initiative are better concepts prior to defining the Story Goal.