This does not change the fact that Wikileaks is legally questionable at best. To my understanding, if you provide a document that is labeled 'classified' by the department of defense to the public, it is a crime.
Your understanding has no basis in existing case law. VISA, Mastercard and Paypal do not need to make legal judgements themselves. Either there's a successful criminal case towards Wikileaks, after which they can act, or there is not. What happened is that behind-the-doors political pressure on American companies caused non-Americans significant harm, and it's not an isolated incident.
Ideals are great things
Luckily for the world, throughout history, some people live by them as well. Your "Founding Fathers" would be one example.