Nobody pretended so - which is the whole point. Thiel could have given his money to a foundation that openly sponsors lawsuits for media victioms. That would haven been for the public good.
Instead he chose to sponsor the lawsuit (and other lawsuits) against gawker in secret because he feels wronged by them with the intent of punishing them. And that's not in the public interest because it can be considered a form of vigilantism.
Instead he chose to sponsor the lawsuit (and other lawsuits) against gawker in secret because he feels wronged by them with the intent of punishing them. And that's not in the public interest because it can be considered a form of vigilantism.