Andre Klapper commented:
In the meantime, that internal memo has also been published at https://github.blog/2019-10-09-github-and-us-government-developers/ which might be a more reliable source than the GDoc.
I'd say that "GitHub considered harmful" sounds like a subjective and incorrect "summary".
As per the previous issue, I'll take this to the d-d-l list for discussion
Thanks. Note that the Github mirror has been discussed before, see e.g. GitHub mirror creates contribution problems in Sep 2017, or Github's pull requests and GNOME on desktop-devel-list in Nov/Dec 2016.