Re: Shioda Gozo Technique
Fully extended in this context means uke has been made to lose his balance.
Mel, if you look at video of multiple uke jiyu-waza by Kancho Shioda, you notice that he does not stay in one spot. He moves around, slipping and weaving in and out of the crowd. By doing this, he is actually forcing the uke to extend themselves, because he simply does not stay at one spot for uke to engage him. In this way, he makes his uke come and get him and that is when aikido technique work best.
He does not stand around and try to grapple with his uke(s). As he moves around, he uses atemi and kokyu-nage most of the time.
I don't even recall seeing any video of Kancho doing any of the kansetsu-waza (wrist/joint locks) type technique when he is dealing with like 5-6 ukes.
Hope this help further.