Not the case at all! The difficult part would be a tortious interference claim. The "defamation or slander" claim would be a piece of cake. The former would be on Marani to prove, the latter would be on a defendant to prove.
A person/company like Marani cannot be called a "thief" without prior proof of a crime and hoping a discover process will provide that proof would be useless as there are limits built into the discovery process.