You are of course right about the ubiquity of English. But for people of Cochereau's generation (he was born in 1924), this was maybe not quite as true as it is now. So while speaking reasonable English has become rather commonplace in today's world, I still think that back then, there was something more remarkable about it. (Maybe I'm also struck by it because I have listened to Cochereau's voice so many times before, and invariably in French.)
Also, CT64's "Roman" saying does not refer to English as a lingua franca, but as the local language of that particular place (i.e. Garden Grove, CA). So what I wanted to say is that it would be difficult for, say, an international recitalist to travel to the US, Japan, Russia, Sweden, The Netherlands, Italy, etc. and speak the local language everywhere.