If I understand Niall's original point a few posts back, the idea is that uke provides the force, and nage/tori only needs to provide the conduits to harmless resolution of that force. Then the throw happens purely because uke continues to attack. (Uke's force throws him.)
But then uke has to provide that energy in their attack -- which comes back to the original topic of the thread -- how much force to use when attacking someone smaller -- I don't believe you can attack with the kind of minimal force Niall described (I'm not going to say no force, because as I've said I don't think that even exists). Defend? More so...
The other thing is for me, I don't think the distinction about conscious vs. unconscious use of force is quite how I'd put it -- because then it's more about how much effort it's taking you -- if it's very very easy for you, you may _feel_ like you're not using significant force, but it might just be that you're really strong. But you might be exerting force in exactly the same directions and using the same muscles as the person who is obviously forcing it -- but since you're so strong it's so easy that it _feels_ to you like you're not really exerting any effort
Like pushing back your hair -- if you had some muscle wasting disease you would feel like you were doing very hard work -- it's just because you're so much stronger than you need to be to move your own arm and push a hair that it feels insignificant.
If I'm helping a small child and they're uke, I very often feel like I'm not using any significant force, even if I'm doing it completely wrong and just overpowering them. They're just so small and light it takes so little effort either way and I can feel like I'm just moving in a totally relaxed way even when really I'm just directly opposing their attack and overpowering them with a stronger force.
This is why I think it's an advantage to be one of the smallest people in the dojo, like me
To me it seems to be more about the direction of the force as well as where it's coming from (if both are right, the amount of force needed really plummets).