I do not se these two as comparable. I think it is an overgeneralisation and wishful thinking.
When guardpassin, most passes do not address only one leg only AND when they do it's very far from arm manipultion seen in ikkyo. Also the purpose is totally different - in ikkyo one tries to manipulate ukes body through the limb. In guardpassing one tries to pass the guard
When being on bottom of mount ikkyo, nikkyo, sankyo etc are completely unusable because you are only able to use your hands for these kind of techniques. And as everyone knows in Aikido we always try to do a technique with our whole body. Which in case of being mounted is pinned between oneself and the opponent.
I have been able to use Aikido wristlocks when breaking posture from guard. But no way can it be considered "doing Aikido" or doing nikkyo, sankyo etc... It's just cranking on wrist a bit similarily as in Aikido...