I knew a guy that was a hippie in the early 70's. He came up with a low draft number and wanted to avoid Vietnam so he joined the navy. Really nice guy that really liked helping people. Volunteered to be a corpman. Could always tell you to the minute how long his tour in Vietnam was.
Like most hippies he was a dope. It was well know back then that most corpsmen wound up serving with Marines.
Even that hippy had a lot more guts than kerry, who joined the Navy Reserves, status "inactive." He was determined to avoid combat, only volunteered for swift boats because at the time, they were not used in combat, only for non-combat coastal duties. When he learned that he and his boat were being ordered inland for combat duty, he raised cain about it, practically refused to go. After that, according to those who served with him, he did nothing but complain and whine. Everybody there was very pleased to see him return to the States.
Corpsman is the wrong Navy MOS to avoid combat. Many were assigned to Marine units in the field.