I think these are two very good posts.
In the Aikido that I teach, resistance is imperative in training, because if Uke can indeed resist a technique, Aiki was not accomplished, and that feedback needs to be given. By the time a technique is "applied", or "realized", if Uke has their balance and control over their own ability to resist and/or manifest a counter etc., something that was supposed to occur, did not.Technique is the simple result and resolution of a successful process. That is Aikido.
Being aware of kinesthetic sensitivity, connection (musubi), position (tsukuri), and loss of balance (kuzushi) allows Nage to find "the path of no resistance" inspite of whatever Uke is doing.
For me, that is proper Aikido, coupled with what we term Kinesthetic Invisibility. It is the ability to move with Uke and connect in such a way as to take away all feeling that "something is being done to them." Without that feeling present, there is nothing to resist, nothing to counter. Resistance on Uke's part is imperative, because that's the only way Nage will know if what they are doing is real, and the path of no resistance has been actually found.
In our method, resistance is both necessary and imperative towards ones development and understanding. In our dojo I differentiate between "tense" resistance that is merely muscling to stop Uke's movement as well as another type of resistance that is more "relaxed" and based upon adapting to your partner's movement and using that movement to execute successful kaeshiwaza.
Imho both are helpful, but it is important for students to understand the purpose of each type and where it can be applied as a learning tool. Muscling down, though often dangerous when in an actual fight, is still quite a common reaction to a technique or movement that is "detected" (iow Kinesthetic Invisibility was not achieved).
Imho part of Aiki waza study involves how the joints and muscles interoperate and align and waza should teach how one utilizes natural mechanisms in the physical structure to execute kuzushi and kake, even if Uke attempts tense muscular resistance. When one muscles down there are 2 options, go in the direction of the resistance and execute a different waza, or use the resistance as a means of finding the correct pathways and rotations required to have the initial waza work as it should.
In the case of resistance through relaxation or adaptation, one attempts to cancel his partner's waza and execute his own by joining with his partner's motion and creating/exploiting flaws in movement or execution. Many may not call this "resistance" but it is, in that one does not simply allow the waza to be executed unless it is correct and truly takes the balance of ones partner.
The only difference here is while the former is resistance by tension, the latter is resistance by adaptation or correct relaxation.
Just my 2 cents.