I can see why you might think of ju based on what I wrote but yielding is not quite the same IME, the yielding I'm talking about is more akin to the idea that aiki is non-dissent, accepting the attack in other words, not the idea of pulling when pushed, pushing when pulled etc. Perhaps it'd be better to phrase it as offering no opposition to the force being directed at you, rather than moving away from a force directed at you.
But thats not uke's part?
In my opinion ukemi consists of two aspects, to give, and to take or receive force.
One, the yang aspect, is to attack, to give something nage can work with, and the yin aspect is to receive nages force like a punching bag that absorbs energy without being harmed.
Both has to occur in a mind of wu- wei (not fighting), any will to fight or to win is counterproductive.
In my role as uke, I often try to get "loaded up" by nages force, for this "load" could be used to send force back to nage, or to send me flying away from him, two sides of the same coin.
It should be possible to switch over at any time (of course not when already flying), thats a thought that is growing in my mind.
Training in this way, it doesn't matter whether you're uke or nage, its both bidirectional receiving and sending force.