How to create outward spiral motion in Adobe After Effects?
That script uses the variable shrink, which paradoxically increases with time. Just make it decrease with time, e.g. by replacing the first line with these two:

var endTime =  123; //how long you want it to take, in seconds
shrink = endTime - time;


Or make the radius the product of the time and a constant, rather than dividing the radius by time, by replacing the first two lines with these:

shrink= time;
radius = 100 * time; //this will grow 100 pixels every second, adjust to suit


Or parent the images to a null, rotate it and scale it up. Then to counter the rotation and scale of the null on each image use this expression for rotation

0 - parent.transform.rotation


and for scale:

100 / parent.scale