Push tests - beating a dead horse
The point of push testing does not have anything to do with being immovable.
In my practice its a training exercise where with help from a partner I get get to assess my degree of body connection, my ability to express dantien (almost nil at this point but getting better I hope), supporting the entire package through the quality of my intent.
On the other side my partner get the same practice opportunity.
Thinking its really about being immovable misses the point.
Its a basic exercise that provides a foot in the door to start some IS/IP training.