onBehavior Add & Remove Defaults

I am just wondering, if you notice these on add and remove behaviors, both declare up, down, left right as = 0. I would expect on remove to be one or vice versa. Why are the the same, and for that matter I suppose, what is the purpose of this default? Is it to simply to reset if error?

function MovementBehavior::onBehaviorAdd(%this)
{
   if (!isObject(moveMap))
   return;
  
   // bind our keys to the keyboard
   moveMap.bindObj(getWord(%this.upKey, 0), getWord(%this.upKey, 1), "moveUp", %this);
   moveMap.bindObj(getWord(%this.downKey, 0), getWord(%this.downKey, 1), "moveDown", %this);
   moveMap.bindObj(getWord(%this.leftKey, 0), getWord(%this.leftKey, 1), "moveLeft", %this);
   moveMap.bindObj(getWord(%this.rightKey, 0), getWord(%this.rightKey, 1), "moveRight", %this);
  
   // set the default values to 0
   %this.up = 0;
   %this.down = 0;
   %this.left = 0;
   %this.right = 0;
}

function MovementBehavior::onBehaviorRemove(%this)
{
   if (!isObject(moveMap))
   return;
   %this.owner.disableUpdateCallback();
  
   // remove the keybinds
   moveMap.unbindObj(getWord(%this.upKey, 0), getWord(%this.upKey, 1), %this);
   moveMap.unbindObj(getWord(%this.downKey, 0), getWord(%this.downKey, 1), %this);
   moveMap.unbindObj(getWord(%this.leftKey, 0), getWord(%this.leftKey, 1), %this);
   moveMap.unbindObj(getWord(%this.rightKey, 0), getWord(%this.rightKey, 1), %this);
  
   %this.up = 0;
   %this.down = 0;
   %this.left = 0;
   %this.right = 0;
}