First of all Github has never been 'a free platform' to begin with and secondly this entire plea is absolutely pointless. GitHub/Microsoft is subject to US trade laws and this is mentioned in their terms and conditions for which they have to comply to. Due to this they have to disallow users who are on the list of sanctioned contries and Iran is one of them.
The problem is not GitHub, its the developers who keep using it to host their private code there and by doing that you have 'agreed' to their ToS. One could easily self-host a GitLab/cgit service at home and do their work from there. The moment you depend on Github in a sanctioned country you risk your account/repository getting banned or inaccessible for others.
The best thing they can do is to quit GitHub and self-host a Gitlab/cgit service (Not on AWS or whatever) locally which that is completely free and for private use. 'Open-source' development was fine without GitHub (Linux, wireguard, etc) so depending solely on Github to contribute to open-source doesn't make sense here.