How exactly could this be done reliably? With shorts you have to commit to a timeframe for not only finding evidence to reject the claim but also for the news to break and convince other investors.
Meanwhile you can be targetted by financial actors that play your positions on the stock market, at times even disregarding the atual company behind it. Further you have to mind monetary policy. If faith in the stock suffers compared to other stock but the overall market just goes up and up, your shorts have a problem again.
Personally, I have no informed opinion on EmDrive, but I have been very pesimistic about companies in the past and I am about some right now. Still, I do not think that shorts are anything appropirate for me. I'd much rather buy competitior's stock than burn myself with shorts or waste hundreds of hours getting into the financial market that I could also use to create value in my actual job/profession
Short the individual researchers? Research projects? Short private funding?
Scams like EmDrive (but there are countless others – "save the planet with X") may be amusing, as long as it's on someone else's dime. Live and let live.
But the minute they manage to convince enough people, whether by virtue or shady marketing, it becomes a political problem. And then it's your problem too, through taxation and "too big to fail", no matter your position. Shorting on the stock market gets you only so far, and only for entities that actually exist on the stock market.
