yes, true, Chris but one (at least) of the very translators is still us, is a great scholar (translator of many languages), artist, zen master and more. I have spent a little time with him and interviewed him extensively and he stands by the translation as you and I would interpret it in normal English, that is "strict" (as in no wiggle room) and "prohibit" (as in not allowing)
So, I don't think you have to take my word for it - I think he would answer an inquiry directly... but do you think the translators dubiously translated the founder's words and translated them back to the founder illicitly for his approval in order to advance their own contrary agenda? (the contents were under M. Ueshiba's direction) or that the founder really meant "sort of prohibited under certain conditions?" or completely opposite- "strictly encouraged?" how many ways of saying that competition is okay in aikido can be mistranslated into "strictly prohibited?" I have no idea - my extemely limited knowledge of Japanese only barely helped me get around there.
I'm not questioning the translation - I've read the original, in Japanese. What I'm saying is that Morihei Ueshiba's own actions don't support that statement as a black and white prohibition against competition in all cases.
As I said, it's quite common in Japanese for people to make "absolute" statements and then perform actions that are seemingly in complete variance with those statements without batting an eye. For those reasons, it's rather tricky to support an argument of an absolute prohibition by decree, IMO.