Again, people only started living longer then they did pre-agriculture very recently. And no one said all grains were bad, Dashel has said repeatedly that rice doesn't seem to have the same effects, because Asians live longer (though their traditional diet is otherwise so far off the western one it isn't a valid comparison, different theories entirely).
My point is none of the research on the site addresses eating flour vs not eating flour. For good reason, the five modern studies that actually looked at it were of a very short duration (though all had very positive results). However, we have an abundance of anthropological evidence which suggests that eating wheat grains is very bad for us, compared to not eating wheat grains, from a time period where there is abundant evidence, though our access to it is very limited. Your link didn't really in any way contribute to the point, which is that without modern medicine of any kind, cavemen literally lived as long as we areright nowand anthropologists believe it is possible that the primary reason for that was the difference in our diet, which was 5% grains and maybe 25% carbs at most (nearly all of which was vegetables, no sugar), as opposed to the current US Government recommendation of 45-65% carbs. It isn't an answered scientific question by any means, but if one of the primary theories as to how cavemen lived as long we do without medicine of any kind is because they ate a lot of meat, fat, and the occasional wild plant or fruit, well, that is worth knowing and not dismissing out of hand. Even if the reason it worked for them is high metabolic output due to constantly activity, performance athletes would love to know that.
Additionally, Harvard is a bright school. Starving people are not healthy. No modern health institute could serious recommend something like the Paleo diet for wide-spread use for the simple reason that we couldn't feed everybody if everyone ate a paleo diet. Grain is almost the only reason the world produces enough calories to feed everyone. But that doesn't mean it is the best diet, by any stretch.