"So how do we know whether Clinton did what he did out of bravery or cowardice?"

I can't call what Clinton did bravery for a fairly simple reason. Clinton didn't start protesting the war until AFTER he became 1-A. There's a reason they didn't let anyone declare themselves conscientious objectors unless they could prove they were fully against war before they faced having to go to it. The presumption was that your reasons for wanting to be a CO were entirely suspect by that point. Why did Clinton declare against the war when he did, only after he realized he might have to go? Tough call.

Likewise, Clinton didn't face his situation head on. He said he wrote a letter to his draft board but never mailed it. At best he arranged for his draft board to postpone taking him and broke his commitment when it became clear he was no longer in danger of being drafted. Doesn't sound like a very noble stand to me.

On the other hand, I can't call him a coward either. I turned 18 in 1973, the last year they held the lottery. As it turned out they didn't take anyone that year and my number was 326 anyway. Would you be surprised to learn I didn't volunteer? Since I wasn't don't really know what I would have done and I certainly don't know what Clinton was thinking, I don't think I'm in a position to call anyone a coward on this evidence alone.