When I asked Lou Ferrigno what he thought about Real Life Superheroes, he thought that the desire to help out was admirable, but said that the only good way to try to fight crimes is to work with the police. He pointed out that there is training and certification that is necessary. And he should know; he has worked with a Sheriff's department as a Los Angeles County, California Sheriff's Deputy, making the jump from Television Superhero to real-life hero.
Steven Seagal has played many an action role, although I don't know that he's ever played a superhero, per se. Still, he got his Peace Officer Standards & Training certificate in California over twenty years ago, and is currently a Reserve Deputy Chief of the Sheriff's Office in the community of Jefferson Parish, Louisiana.
Another superhero actor-turned-crime fighter (who wasn't at the convention, as far as I know), Shaquille O'Neal, also went the route of joining forces with the police to do his part to stop evil-doers. Back in 2005, Shaq became a reserve Police officer in Miami Beach, Florida