Github has dabbled a bit too much in politics in recent years TBH. It doesn't surprise me that projects like GNOME would take pause at that, among the other reasons people are listing.
When my company was evaluating open source cms/hosting solutions, Github was quicky removed from the list of candidates for this very reason. Their criteria for removing software projects was deemed too unstable to depend upon, and the company is too small to garner the same respect from github as bigger companies.
