Not sure if the backlash got to them or they got word of potential legal issues caused by doing this, but I can see their GitHub page and its associated repositories just fine now:

https://github.com/w-social-eu

But I do kinda wonder the legality of this sort of move anyway. If other people contributed code and didn't agree to some terms of service saying their work would become the property of the project owner, would it even be legal to make it closed source under a different license?