I'm not following you Mark. Are you saying you don't think those are O Sensei's words? I no longer have a copy of the book so I can't check the source. John Stevens, who speaks fluent Japanese, translated and compiled the book. He is a respected and world-famous writer and translator and expert on many aspects of Japanese culture and is also an aikido teacher. I'm sure you will understand that unless there is evidence to the contrary I will stick with his opinion.
I would wonder where the quote came from, who said it, and what the original Japanese text was. John Stevens is known to use translations but not to give citations as to where they came from. He is also known to have omitted parts of sentences from translations, changed meanings from other parts, and to translate ideas according to Japan's wishes.
IF you had to rely upon someone's translations to build a nuclear reactor or to do heart surgery, would you rely upon someone who worked like that? "Hey, let's take out this section where it talks about an important part of cooling a reactor because it really doesn't translate well."
But, if you want to rely upon Steven's translations ... that's up to you.