Hey gulfstream piper, I would tell your friend to apply anyway. There are no questions about "what is the current status of your commercial pilot certificate etc. It does help your possibillities to be a pilot. One thing you do want to make sure of though is that he is 100% honest with them. If they do ask or want clarification just be forthright. There have been some people hired with a lot of "baggage" in the past but they were honest and made it through it. I hope this helps. Or you could give human resources a call and ask them?
Good advice -- just make sure he does NOT lie about anything. There's nothing worse for your career than lying on the application. I think it will depend on what the violation was that resulted in the suspension of his certificate. If it was a bad FAR violation (or multiple FAR violation) or careless/reckless operation it certainly won't do a lot to build the government's trust in him as a controller. If it was something more innocent that he addressed appropriately and responsibly it might not be a big deal. Just depends I think. But he should certainly still give it a shot.