Is it the “exploding and returning to shape” element you’re trying to recreate or do you want the circle to form a square?
If it is the first one, you might try a displacement map or an expression to knock layers and then return them to a location something like:
var pos = transform.position;
nudger = thisComp.layer("Nudger").transform.position;
maxDisplace = 300;
dist = length(pos, nudger);
linear(dist, 500, 0, value, [maxDisplace,maxDisplace,maxDisplace]);
or animating the the Air > Spherical field in Particular.
If it’s “circle to square” I think you’ve been given the best approach, fake it using time remapping and fading.