I'm not sure people saying this know that the author is one of the "core developers" of Django. It is safe to assume that his expectation of "open source" is not far-fetched at all.

While you may have a point, language developed with closed process and just the source published in one of the famous code hosting sites need not emphasize on having a "community"[0] if it is not really looking to hear things from the "community".

[0] - https://elm-lang.org/community