What you're proposing requires him to sell his time instead of his work (which was already a portion of his time). It is impossible to scale that type of consul

What you're proposing requires him to sell his time instead of his work (which was already a portion of his time). It is impossible to scale that type of consulting work to multiple clients because you'll always be limited by your available time. The spirit of open source isn't so sacred. In most cases it is hundreds or thousands of businesses benefiting financially from the work you've done.