Why is this structured as a loan? It sounds like it's structured in such a way that he isn't interested in getting paid back. Is it so he can exercise control in a weird scenario like a buyout? Is it some weird tax thing?
Startup funding that looks more like debt than stockholding isn’t all that weird, and has various implications for exit scenarios.
If you wanted to create something similar to a nonprofit, this is a way you could do it while protecting it from vultures.