Have you tried pair-programming with him? If you show him version control in action, including jumping between branches, looking back through logs, and perhaps an "oops" followed by rolling back to a good version, there's a good chance he'll see the benefits it would bring him.
If he is worried that people will tread on each other's branches, then maybe it would be advantageous for him to have a separate GitHub fork of the project and collaborate via pull requests, like in the open-source world. That way, he will have full control over what is allowed in his version of a branch.
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Have you tried pair-programming with him? If you show him version control in action, including jumping between branches, looking back through logs, and perhaps an "oops" followed by rolling back to a good version, there's a good chance he'll see the benefits it would bring him.
If he is worried that people will tread on each other's branches, then maybe it would be advantageous for him to have a separate GitHub fork of the project and collaborate via pull requests, like in the open-source world. That way, he will have full control over what is allowed in his version of a branch.