It wasn't his "shot". NOT getting boxed in doesn't mean that he would have medalled--but GETTING boxed in definitely meant that he would NOT medal.
Allowing himself to get boxed in WAS his "shot" at not medalling, and he took it.
Plus, even if your interpretation of "what he really means" is accurate, any observation like "at the time it looked like such a likely-to-fail shot that I didn't take it" is the very definition of the lack of courage I was talking about.
"It's not that he lacked the courage this morning, just that he didn't yet know enough to know when to exercise it."
You don't "exercise" courage, you implement strategy by "exercising" tactics. Courage is there all the time, it manifests at all moments. You suppress courage with mental exercise. Courage happens only when your actions are bigger than your self, when you lose your sense of self to the bigger situation. That can be uncomfortable for people, and that is what courage is--the ability to let go.
That is why great performances are described by their performers as effortless, that is why Montsho was up and waving while Felix was on the ground sucking wind, that's why Bolt said he could go right back and run 9.69 again, that's why they often don't remember exactly what happened.
Symmonds knows exactly what I'm talking about, no doubt he's had this at other points in his career.
I think he's run enough high-level meets, though, to have it in a championships final, and have learned already long ago that "CHANCE plays a massive role in these races".
Unless he's Rudisha, which he's not.