I though that the people that leaked stuff would get caught but he showed his face.
Not how that works.
When you leak you can be "prosecuted" three ways: 1. Breach of contract; 2. Tort / Civil; 3. Blacklisting.
When leakers ask to be anonymous it is because they are under contract- either an employment contract or NDA- that obligates them to not leak materials or suffer punishment that they agree do by signing the contract and accepting work / payment that gives them access to confidential materials.
Someone like Umberto is not under contract to protect information, but instead he entices people to
break their contracts. He pays them, or hooks them up, or compromises them until they tell him their secrets, which puts them in breach, but so long as Umberto never gives up his source, arguably no one will find out. Umberto can be sued for causing economic damage or enticing people to break their contracts, but it's a tough case to prevail on because there are laws protecting journalists and proving damages can be tough. Nonetheless the studio is sometimes forced to sue simply to make an example out of someone, even if they don't anticipate prevailing the legal costs of defending oneself is still a tax.
Lastly, most studios engage in horse-trading with journalists, agreeing to provide exclusives if the journalist will hold off on a story so they can control their marketing campaigns, etc. If someone leaks too much without first communicating with the studio, they can get blacklisted and it may limit their access to future events, stories, and employees (if there's a studio-wide alert: "Meet with so and so and you're fired").
Most journalists / studios play ball... if they don't, it doesn't really cost the studio that much money to put private investigators on your ass 24/7 until they identify the leaks... so there's a polite push and pull. If a journalist goes too far- like publishing an unreleased blockbuster's script- you can expect them to more or less be done.