Rubbish. Shortsellers help to provide equilibrium in a market. They help to dampen euphoria in a rising market. And, since they are usually theprimary buyers when a stock is droping, they also dampen panic and despair. Of course when a stock rebounds, the unfortunate shorts provide much of the fuel. Shortselling, in one form or another, is essential to healthy markets.
By the way, it's almost impossivle to make money shorting into a rising market, much less a market rallying as biotechs have recently. Most of the "shorts" on boards like this are really folks who've bought some cheap puts, which is rather like buying a lottery ticket, only with worse odds. They hope for some totally unforeseen event which will drop the stock dramatically. This explains their frequent hopeful exclamations on the order of "This POS going to $10!"