To be clear, despite this announcement being posted to gitlab.com (i.e. the "hosted GitLab", which can and will remove you/your/repo any group at any time), the GNOME project is self-hosting their own gitlab instance. So they are indeed insulated from such hypothetical damage.
I would be shocked if there were not DMCA take-downs that left some people feeling raw - honestly how can you avoid that - but this sort of thing does not attract much notice these days.