OK, in case anything is unclear - nobody here ever said Ueshiba or anybody else never took ukemi.
Of course, anybody is capable of taking ukemi if they choose to do so. The can also roll around on without anybody being around for miles.
FWIW, Dan has taken ukemi for me many times.
Not being contentious here but I would say this: When being Uke as a teacher then what are you doing?
I for one am teaching the nage how to 'throw' and indeed how to 'throw' me.
Thus any teacher worth their salt is teaching how to.
So any statement of how another couldn't shows a lack of good teaching from that viewpoint, by the uke.