Ah, from the front page of Aikido Journal, comes this article. Seems Ueshiba kept having people push and pull him into his older years.
So, why is it, that something as fundamental as this ... something Ueshiba did most of his martial career (after training with Takeda, it seems) ... that this hasn't spread throughout the aikido world?
can't speak for anyone else but our organisation does this.
I imagine most styles coming from Tohei's side of things would practice this, along with the other forms of testing; some of which mentioned in his books.
This example above sounds like a test called "standing naturally".