My knowledge of the efficient market hypothesis is sketchy, but I thought that the EMH states that the actions of each individual participant in a market will, on average, be equal to the “true value” of the asset they’re bidding for (I’m assuming that true value is a synonym for, say, a factor’s DMVP in final equilibrium). In this case John James’s actions (making the threads) would be an outlier and the actions of the other individuals (not making the threads) on the Mises forums would average together with his and would be equal to the true value of the low-content threads. Take this with a grain of salt; EMH is certainly not something I profess any expertise on.