Sources to improve the article, and which tend to demonstrate notability, from the AFD:
Keep I originally speedily deleted the article because it was unreferenced and had WP:BLP issues due to unreferenced statements about Joe McCain's personal life in the first posted version. But the principle that relatives of politicians are not inherently notable certainly does not mean that they are inherently NON-notable. Also, I believe that the precedent of what has been kept and what has been deleted in AFD actually does provide guidance for future AFDs: We have kept several articles about relatives of world leaders or political candidates who are notable only as a result of their famous relative, but who have substantial coverage in multiple reliable and independent sources, thus satisfying WP:N. There is no requirement that this coverage be completely unrelated to the career of their politician relative. For Joe McCain, there are numerous article in newspapers over at least the past 37 years, long before McCain was a political candidate. There is coverage of Joe McCain sitting in a bamboo cage in Los Angeles, eating simulated POW food to dramatize the plight of POWs, as printed in The Independent (Long Beach, CA) Nov. 27, 1970. There is  "In behalf of POWs, will ask 'doves' to sign petition" (Associated Press, December 31, 1970) as printed in Florence (SC) Morning News, Dec. 31, 1970, page 1 (via NewspaperArchive.com (subscription). This is a feature story about Joe McCain and two other brothers of POWs travelling around the US circulating petitions to be presented to North Vietnamese representatives.   There is a 86 word passage about him in "Powerful Virginia Machine Digs In to Tackle McCain," By Francis X. Clines, The New York Times, February 25, 2000. See "MCCAIN WILL PRESS CAMPAIGN TO REFORM GOP, BROTHER SAYS" March 8, 2000, by Tom Ernst, The Buffalo News which has substantial coverage of Joe McCain, partly behind paywall. See "Brother on Board; Joe McCain Isn't Steering the Campaign, But He's Proud to Be in the Back Seat" by Frank Ahrens,  The Washington Post,  February 3, 2000. which is certainly a story in a major newspaper devoted to Joe McCain. "WORLD VIEWS: U.S. losing friends over torture" Edward M. Gomez, special to SF Gate (San Francisco Chronicle), November 15, 2005 has 126 words about Joe McCain on the Abu Ghraib torture scandal and his brother. "Theater;Falling in Love With Love ;At GALA, Garcia Lorca's..." Washington Post, Feb 4, 1991 talks about an about an actor named Joe McCain, but it is behind paywall so it takes further research to see if it is this Joe McCain, who is said to be an actor.