The statement on The Zipa & The Zaque Move Toward rule is "If unit cannot improve position with a single move, it will stay put". 

The idea here is even if Zipa heads one direction and then it gets bottled up, she won't turn around and back track the other way even if its totally open. 

Instead, she will remain put and may even roll a King's Rush allowing her to swap with another unit in front of her. 

But to be clear, at the start, if both paths count out to the same # of hexes away from the Pillar, its your choice which route she takes.