Of course. Having said that you have to take a look around and decide if the conditions are remotely in your favor, right now, and when/if things don't pane out in 6-12 months. The economy (not the stock market) isn't great, finding another job without much experience in the current state of the tech industry might look even more bleak. I graduated right after the dot com bubble burst. I took the calls from recruiters offering me sign-on bonuses and other crazy stuff during the bubble - I declined and chose to finish school instead. A year later after graduating I moved to Boston and heard first-hand accounts of developers driving cabs to make ends meet when things imploded.
It's one thing to take a high risk / high reward chance, but swapping a steady good-paying job for effectively an unspecified unpaid role doesn't seem like that. If he's willing to work unpaid, he's more likely to get a low-ball offer if/when the company decides to employ him.