At the risk of committing LRC messageboard sacrilege, I'm going to take the middle ground here...
It is cause for concern. I think the guy talking about "basic competitive instincts" or whatever has it right. If he was that close to giving up, what must his mindset have been like at the time? I'm guessing not that great. If he were that driven to compete, run fast, and maybe even win at that point of the race, it seems more likely he would have jumped back on the track immediately, without any logical thought, and continued to compete even more intensely than before. We can't know what he was thinking at the time, but it's quite possible he was thinking negatively before he quit.
On the other hand, he did have to make the decision VERY quickly. Everyone here should know what it's like to be in a race - it's a whirlwind, time takes on different properties, your body and mind are in the eye of a hurricane. It's easy for me to imagine how his decision making, when he was certainly desperately focused on staying in a groove as anyone is going to be near the end of a serious race and suddenly found himself off the track, was compromised. He explicitly stated that it was a mistake, and I am going to give him the benefit of the doubt that he truly believes that, understands why, and is indeed going to return to the track with more fire than ever.
It was a lame move, to be sure. It's not want you want to see for him. Seasons and even entire careers can be defined by how we react to physical and mental challenges in these important races. I know that the times I didn't dig deep and give my best in races haunted me for a long time and certainly affected my later performances, but they are not obstacles that can't be overcome. As I said, Solinsky has given us plenty of gutsy, balls-out performances over the years, so I'm going to wait before labeling him a quitter.