That's very poetic, tattered.
However, I don't know how much reality there is in your optimism. There may well be some CEOs out there who don't know enough not to use a double negative in their formal writings, but I bet they are in the minority... As are managers and business owners who cannot string together a proper paragraph. Business plans that are written in poor english won't get the attention of venture capitalists, and for good reason. Managers that can't put together a decently-written quarterly report will get replaced--unless of course their bosses are equally ignorant.
Proper language is very basic, as you said. Failure to master such a basic thing speaks volumes about a person's overall aptitude and work ethic. In a world where competition is as intense as it is, why bother going with the guy who is competent but can't speak or write well, when you can get a guy who is both capable and coherent? It's much like personal hygiene, actually--not necessarily essential to the business at hand, but without it, you generally wouldn't get in the door... If that little chuckle you mentioned occurred during the interview, I doubt it would be much of a laughing matter for the person seeking the position.
For a native English speaker, I just don't see an excuse--especially when so many foreign-born Americans have mastery of our language.