My pennys worth. If uke simply follows tori without tori having made uke move this to me is a waste of time.Somebody making big circles /orbiting around tori without their centre being taken might just as well be ballroom dancing [no disrespect to dancers by the way ].Tori must apply kuzushi and ensure that ukes posture is broken. If ukes posture is not disturbed uke will 1. be still balnced.2. if uke does go down , ukee is colluding with Tori.
You will not see any judoka in shiai falling over .Only time there is total collusion in judo is doing kata [nage no kata in particular ] .Tori /uke work as a unit , each responding to the other.