It looks like he's not technically breaking the law: the beach remains public, the issue is gaining access to it, which there's apparently no public mandate for (the article notes that previous owners of the property charged a small fee to go through).
Real estate law varies from place to place. It's common to require that a blocking property allow access to the blocked property (an easement). This guy's property seems to be blocking access to public property.
Lawyers will huddle, and I'm guessing in the end that people will again have access to public property.
