Zealous community member wants to help
Mz: Some people just like to feel helpful/needed and like to spend their time working on stuff they believe in.  If no money is exchanging hands, your best currency is to make them feel respected and appreciated.  But, as others have suggested, don't give access to something that might lead to regrets.  And start small and let the role grow.  It's much better to do that than to give too much to the person, have a bad experience on both ends, and try to curb it back.