I don't think its fair to attack someone for something they didn't do, especially when that something may have been out of their control. I was in the Vietnam era Navy, but I never fired a shot in anger and was never shot at, how could I take any credit, or blame, for my activities? After all, I deliberately joined the Navy because I knew it was a safer, more comfortable service. To attack someone who didn't go at all, for whatever reason, would be the height of hypocrisy. Even the idea that simply participating is enough, is bogus. Everyone participated in the war except for the protestors and the draft dodgers.
Just paying your taxes and not expressing dissent is participating, a tacit "Yes".

However, I remember the way McGovern was savaged for his anti-Viet War views by the Nixon tribe, and it was disgraceful. The same old thinly-veiled charges of effeminacy, weakness, cowardice. And it wasn't until many years later that I learned about his war record, he never made it part of his campaign, and he could have easily have demolished Nixon with it if he had chosen to publicize it.