He was led on with the promise of a better salary.

THIS right here is the part that drives me up a wall. Earlier in my (admittedly still pretty short) career, I'd probably have done dev work for free, if only to get some "official" experience and work with some devs I could learn from. But it's an entirely different situation when someone is working for far less than they're worth because they're being lied to. That's not a CEO giving someone a leg up despite lackluster credentials, that's just a CEO stealing labor under false pretenses.