Though he served two tours, there was a big difference between serving on coastal/river patrol and being on a big ship at sea which is not in harm's way.
I will take issue with you somewhat. I served 8 months off the coast on an LPH (including 65 days straight at sea) and one year in country. Just because you were on a big ship didn't mean you were out of harms way. A good friend of mine almost lost his life on the USS Oriskany, CVA 34, which had a major fire that cost 44 men their lives in Oct 1966 off the coast of Vietnam. There were plenty of lives lost and others injured on our ships due to accidents and handling ammo, etc., associated with high temp ops in a war zone. I received combat pay for both assignments, at sea and ashore.
But then by the same token, GWB should be given full credit for flying the dangerous F-102 "widow maker" supersonic interceptor in the other war going on, the "Cold War." Plenty of F-102 pilots died, just flying that jet. Anybody who flew interceptors in the USAF in that era knows you didn't have to fly over Viet Nam to risk your life. I think something like 20% of all the F-102s ever built....crashed. With a lot of pilots in them.