Well it was said (attributed, anyway) to Max Weinreich (https://en.wikipedia.org/wiki/A_language_is_a_dialect_with_a...) who was a professional linguist.

Notice that it was said in Yiddish which, of course, did not have its own navy or army. So it may have been said with a tongue in cheek, especially if the story relayed by Weinreich at the link is correct.