Most of the comments here seem to be saying that the case was decided incorrectly because the text of the law was clear and the intent doesn't matter. However, there are lots of other cases where the text of the law is equally clear and yet SCOTUS has ruled that intent matters. Let's start with the First Amendment. It's obvious that slander laws run afoul of the plain text of the First Amendment. Which part of "Congress shall make no law..." is unclear? None at all. Yet SCOTUS has ruled slander laws are allowed, as well as laws preventing inciting a riot (e.g., yelling "Fire!" in a crowded theater).
For another example near and dear to conservatives' hearts, consider the Second Amendment. The Roberts court has ruled (District of Columbia vs. Heller, 2008) that the Second Amendment establishes an individual right to carry arms, despite the fact the amendment only mentions carrying arms in the context of a militia.
With the current case, the intent of the law was clear (and most of the drafters are still around to ask), so that's what SCOTUS used. Judges aren't just implementations of parsing algorithms that spit out yes or no results based on the text of the laws.