The majority decision, written by Stephen Breyer, really just keeps going back to the fact that Aereo looks just like what those cable companies used to do… and therefore, given that Congress changed the law to outlaw that, Congress must have meant that Aereo should be illegal as well. The majority seems to view things as a black box, ignoring everything in the box. It just says “well, to end users and to networks, this is identical to the old cable systems.” As for the very careful steps that Aereo took to comply with the law? The majority just brushes that off as meaningless.
This is what happens when technically illiterate people are set to rule over technical matters.