Basically Namecheap should remove their account for "electrumdiamond.org". But it seems to be difficult to contact the Namecheap support at all.
I did a follow up and I can now confirm that the scammer's domain is no longer active.
The new GitHub profile was also removed.
https://github.com/Electrums/
Thanks to whoever took their time to report both the domain and the GitHub profile for abuse.