Here's the problem: he wants to work at a startup. A startup, if successful, that's at ramen profitability - meaning, there isn't any cash for you even if they wanted to pay.
If you've got a VC-backed startup with cash, they're recruiting interns through the traditional processes anyway, where this guy is going to have trouble standing out.
So, the pay could be in something other than cash, if the startup is anywhere near successful bragging rights would be one thing that would be valuable, a really good reference would be another.
I remember that when I was 15 I worked for free in a computer store, the deal was simple: I could play with the computer as much as I wanted, but if a customer showed up I had to explain how it worked as good as I could (Radio Shack in Amsterdam). So, even if I didn't get 'paid' in money I got to play with a computer that I could not have afforded for several years.
Maybe something like that is feasible in this case.
If you've got a VC-backed startup with cash, they're recruiting interns through the traditional processes anyway, where this guy is going to have trouble standing out.