samtto I personally don't think this is our problem. FontAwesome is an open-source project available from multiple mirrors, and the legality of using FontAwesome is probably not banned in any country.
FontAwesome's own website appears to be blocked in china, probably because they are hosted on some hosting blocked by the Chinese government. This is a problem that should probably be discussed directly with FontAwesome.
If they are not willing to setup an official documentation for chinese users, nothing prevents people from mirroring the official docs. I tried finding discussions about this issue at FontAwesome but couldn't find anything. It's probably worth contacting them about it. Maybe they are not even aware their website is blocked in China.
If you know of any drop-in replacement that chinese app developers commonly use in place of FontAwesome, I would be happy to hear about it.