Cases would be difficult to prosecute because of the 'discovery' process. The prosecutors would have to produce evidence that GW is real. They can't. A 'consensus of scientists' is not evidence.
More likely, the pushers of GW could be prosecuted for perpetuating the hoax. RICO: The Racketeer Influenced and Corrupt Organization Act.
Racketeering refers to criminal activity that is performed to benefit an organization such as a crime syndicate. Examples of racketeering activity include extortion, money laundering, loan sharking, obstruction of justice and bribery. [from
investopedia.com]
The so-called deniers are not benefitting from the GW hoax, but those perpetuating the hoax are.
Chances are, they would, because the jury would likely rule in favor of AGW. Plus, you also have the issue of well, judge bias where the judge is in favor of AGW. In an ideal setting, where you could be sure of how the judges base their assumptions on what can be solidly proven, then you would be right. However, you can’t be so sure in today’s world.