Not smart to refuse a breathalyzer. Most states have Implied Consent laws and I believe its in the FARs as well. There was a chance he could have passed, but by refusing he is going to have a hard time fighting the charge in most states. His medical should be safe, but if the FAA goes after something, it will be his certificates. Talk to an aviation lawyer. I believe AOPA also has legal advice if either of you are members.