A code hosting service that can be persuaded to not host projects that can inconvenience the government (or party)? I guess this sounds attractive to a certain kind of people.
Where "certain kind of people" would be "all people in China" since their options would be limited to either (a) use said service or (b) not access the blocked original version.
Ceteris paribus, a blocked service is better than no service, yes. But (1) VPNs exist, (2) decentralisation is surely not so infeasible as to rule out evasion of various blocks, and (3) the government might even decide to prioritise scientific development over absolute political control. (Certainly it seems that the scientists within the party are agitating for freer access to foreign papers.)