The quote came from where originally, the autobiography? I don’t know where you got it, but without acknowledging logical fallacy when it arises, we don’t have much to work with in terms of science and social discourse. That doesn’t mean I’m calling his “ideas ‘wrong’” in general! Nor do I think you misinterpreted his writing. The statement as quoted is logically false and can be proven as such, and several others have already stated the facts that disprove the statement earlier in the thread. In his math, it holds true, and he’s entitled to his opinion. Doesn’t make it fact.
Not sure what you mean by the latter about playing “‘Three Blind Mice’,” but in terms of what was in that clip, he was answering a question about enjoyment and utility of Slonimsky, he was not posting the subject of this thread. I’ve already stated that many of us prefer enharmonic spellings. It’s possible to hold two ideas at the same time (that key signatures exist for a reason and that they aren’t necessary in a particular context), and it’s possible to read more into a statement than is there (“dismissing the idea of key signatures as being archaic”). In fact, he explicitly left it open ended with mention of horn players. We can agree to disagree on the interpretation.