Eastman along with the candidate tried to enact that legal theory. And unlike Trump Gore actually had a valid reason. Trump and Eastman sought to try to fabricate a reason to enact their legal theory. If there actually was election fraud like they tried to say there was than they did nothing wrong. It was just a means to disenfranchise voters not protecting the integrity of the election.
Gore had no better reason than Trump. Both disputed the results. Gore lost Florida and Dershowitz sought to overturn that which is his right just like Eastman.