That isn't correct. He complains in incredibly hyperbolic terms about short-selling in general. For example, "It is important to understand that selling a stock short is not an investment in American enterprise. [...] A successful short manipulation takes money from investment in American enterprise and diverts it to feed Wall Street's insatiable greed—the company that was attacked is worse off and the investing public has lost money. [...] This national disgrace is a parasite on the greatest capital market in the world."

The tone of this is just short of complaining about "the international Communist conspiracy to sap and impurify all of our precious bodily fluids". But what they say is all exactly true of all speculation, short and long. The only thing that's actually an "investment in American enterprise" is buying new shares in a public offering. The rest is just gambling on the outcome to "feed Wall Street's insatiable greed".

Indeed, one could argue, as short-sellers do, that unchecked positive hype is more damaging to market participants, because it obscures the underlying value of a instrument causing people to overpay. When people buy something overvalued, they've already lost money; they just don't know it yet. Shorting helps keep those dastardly long-sellers in check, keeping them from stealing the hard-earned money of retail investors everywhere. If shorts manage to momentarily drive a price down below the intrinsic value, why they've just created a bargain for savvy investors. They are in fact doing a public service that otherwise would have to be performed by intrusive regulators. Etc, etc.

I think the truth lies between. Speculation, short and long, is economically valuable because it aids in price discovery, creating a liquid market so that actual investors in a company can exit, freeing up capital for further new investment. One could argue (and I often do) that we have way more speculation than we need to fill that economic purpose. But complaining bitterly about just the skeptical side of that speculation is like arguing that Hacker News should only allow positive comments about startups.