> *Edit : it does seems like a good idea to disable the feature on your local `ssh_config` in case you or a software you use connect to an unpatched evil server.

The vulnerability is in the OpenSSH client, not the server. ssh_config is the client configuration. Unpatched servers are not relevant and putting this option in your server configuration (sshd_config) will simply make it not start, because the configuration is invalid.