This is my best guess and it's probably not right, but it was fun to speculate. I'm going to say that it's all about relativity.
Picture a story about a bomb set in the middle of a crowded area. The Story Goal is to have everyone live. The solution is to not be near the bomb when it goes off. So is the solution to Avoid the bomb, or to Pursue safety? I'd argue that the answer is "yes".
The place I'm coming from with this is that Melanie has described Dramatica as the internal, or mental, equivalent to the way we see the external world, and has gone as far as to suggest that K/T=AD within Dramatica is the mental equivalent of E=MC2 (sorry, not sure how to notate "squared" when typing).
Basically, there is no direction of "up" in space. You have to set "up". Once you do, you know where down is and you restrict "left" and "right" to a plane perpendicular to "up and down", but "left" and "right" still have a 360 degree range of possibility. But once you set "left" you know where "right" is.
I'm wondering if ,similarly, there is no direction of "Pursuit" until you set it. By defining the Protagonist as being in Pursuit of the Story Goal, you force the Protagonist in the example above to pursue safety, even while avoiding the bomb (can you pursue "avoidance of the explosion"?), and thus set a frame of reference for the rest of the elements.
In the same way, perhaps you could theoretically define the Protagonist as the one Opposed to the Story Goal and set an entirely different frame of reference for the rest of the elements and free up Pursuit and Avoid to be used toward or away from the Goal.
Anyway, there's also this:
The true Archetypal Protagonist pursues the solution against the Antagonist. In other stories a close cousin of the Protagonist shares all the same elements except he tries to avoid the Antagonist's plan. For the Pursuing Protagonist the goal is to cause something. For the Avoiding "Protagonist" the goal is to prevent something.