Alston was wounded in the head, a "graze" apparently. Also shot in the arm. No reason to douct that story.
Here's a caption I found to the pic above:
"PCF (Patrol Craft Fast) 94 crew in March 1969, from left, Gene Thorson, David Alston, Thomas Belodeau, Del Sandusky, and John Kerry."
What picture are you referring to? What post?