Actually Roberts called it a tax in his opinion...as did Mitch McConnell
"So what did Roberts actually say?
"The text of a statute can sometimes have more than one possible meaning," the chief justice said in the majority opinion. "To take a familiar example, a law that reads 'no vehicles in the park' might, or might not, ban bicycles in the park. And it is well established that if a statute has two possible meanings, one of which violates the Constitution, courts should adopt the meaning that does not do so. Justice [Joseph] Story said that 180 years ago: 'No court ought, unless the terms of an act rendered it unavoidable, to give a construction to it which should involve a violation, however unintentional, of the Constitution.' ... Justice [Oliver Wendell] Holmes made the same point a century later: '[T]he rule is settled that as between two possible interpretations of a statute, by one of which it would be unconstitutional and by the other valid, our plain duty is to adopt that which will save the act.' ..."