I also agree. I got hired at my regional and now Delta with a skeleton in my closet (not a DUI). In both cases, the incident became a positive focus of the interview. It made me stand out (in a good way) from the others.
Be humble, forthcoming and owe up to it. There is nothing wrong with admitting you made a mistake. But more importantly, be able to explain what you learned from it and what you're doing to mitigate a repeat.
The only hindrance will be the timing. If this is a very recent event, they may not touch your friend for a few years. They want to see that this is an aberration, not a possible trend. With so few hiring, this may not be an issue right now.