Dunno about fine, but my opinion is that in either omote or ura, nikyo is about controlling the center through the nikyo lock.
Most people seem to perform the omote without the nikyo lock and rely on the elbow for control. To me, that is ikkyo with an incidental hand position on the wrist that looks like nikyo, but it is not nikyo as the center is controlled through different means.
Pins are a separate issue and I suggest that you can perform an ikkyo, nikyo, sankyo, etc. pin after using an arbitrary ikkyo, nikyo, sankyo, etc. technique. What we do in class is usually a rote kata pairing the ikkyo technique with the ikkyo pin, the nikyo technique with the nikyo pin, etc., but a totally arbitrary pairing only intended for learning.
This is such a true statement! I often tell this same thing to many people that I train with. I show them that it is not enough just to have a nikyo or sankyo "hold" without actually applying the nikyo or the sankyo. Incidental contact, such as what you mentioned, does not control the nage, especially when they are very strong. The same thing applies for applying the pin. One should always keep the applicable grip on the joint while making the exchange from one side to the other in order to apply the pin. Likewise, the pin applied without the actual application on a nikyo or sankyo is not well advised.