Neutralizing what the opponent is doing. In Aikido this is a term often used and connected to hara or earthing Ki etc. It is also described as moving in alignment with or harmonizing with. Various views and ways of putting it.
So here I shall give a view to introduce a perspective I haven't seen put much yet I believe to be true to the ways of O'Sensei.
Rather than to neutralize I believe he was merely being neutral. He was operating from neutrality, the spirit of neutral.
Now of course there is the spirit of loving protection etc. all part of the whole so where do I get this view from? Well I get it from the statements and practice of non-resistance. So to put active non-resistance into a terminology that can be better grasped as a starting point then I would say it is the spirit of neutral.
This removes us from the whole 'logical' duelistic framework of looking at things for you look at them from neutral. With non-resistance. The person attacking or holding expects resistance of some kind and yet if you give neutral Ki you are in fact giving non-resistance, untroubled by the 'illusion' of should do this or must do that but merely following its path. So what is it's path? It is the path of non-resistance, the lines that lead to techniques. The paths of non-resistance.
From neutral you can thus see through. Take someone giving you an angry comment or any other negative comment or emotion. Then through being neutral and looking from neutral you can see through that emotion rather than having to contest it and challenge it with an equally negative emotion. Now if you are neutral for real then the emotion wouldn't disturb you in the first place.
Thus this is a perspective on active neutrality the result of which may seem the same as what is described generally as neutralizing but is in itself totally different. Active neutrality just stays and moves as itself and cannot be affected by negative force thus the force having nothing to go against negates itself.
So I say from this view that the feelings experienced by those when using hara ie: compassion, love etc are also inherently non-resistive energies and thus follow thos natural fluid non-resistive paths of motion. They are active non-resistance or active neutrality which in turn shows you that neutrality is not a passive thing.