One of the ideas in the article is that rather than focusing on any one thing, such as breath, or one-point, or alignment, we instead allow what is arising to arise, without judgement, without resistance, without identification. Because by focusing on a specific object, we exclude and introduce an element of control - which is immediately going to set up judgement. And from there our "practice" then becomes one of constantly judging right/wrong and wanting to control. This immediately begins to narrow the bandwidth of our experience, to the point where we're practicing through a restricted channel.
Instead of focusing on a single object, if we, instead, just observe and allow the process to arise as it will, something interesting happens; we begin to detach from the process itself, rather than identifying ourselves with it, or even as it.
Firstly I would say as an exercise that could be more to do with a seated yoga or some such rather than Aikido.
Secondly saying that focusing on something does not lead to judgement so I believe that statement is incorrect and that method is indeed vital to Aikido.
The difference is this: Basically what the article is referring to and you referring to as a practice is actually contemplation.
The focusing one is meditation. Two different things. Aikido is moving meditation.