Yes, as answered in another branch, it's possible and reasonable to setup continuous / daily backups, if you're using a hosted Git service (Github or not). This will mitigate the risk of losing access to the code.

It's not advised for these Iranian developers to use any Github-specific features, such as issues, wiki, CI, because losing them will cause disruption / knowledge loss.

And then the reason to use Github specifically, instead of something else is quite low.