I have to admit that I'm a bit surprised by the unanimous opinion here. I've never offered any unsolicited advice at work either, and I don't plan to start doing it. I figured someone would pipe up with an example or two of an instance where things worked out well. Like I said, it's not a risk I'm willing to take with anyone other than a very close friend.
Are you some how responsible for the person? Is his image causing problems for the company?