Shorting is not evil. It is just making a bet that something will be worth less in the future. It has no more moral implications than choosing red rather than black when betting at the roulette wheel.
Yes, sometimes huge short sellers can "convince" the market that a company is weak and should be worth less. How is that any more morally repugnant than when analysts or the media "convince" the market that a company is strong and should be worth more?
I admire Zeev in his ability to make money only going long, but I attach no moral issues to going short.