It was “forbidden” to be collected like a tax. They could not garnish for it they could not penalize you for not paying it...it was not to be considered a tax.
Until Roberts said it was.
Even Ginsburg in her ruling used the commerce clause as justification to rule the law constitutional. She said that yes the government could compel you to act because you would eventually act[need healthcare] and this was too important. Words to that effect. [Scalia said that was analogous to saying you might one day buy another car: the government cannot compel you to do so right now.]
His dissent was masterful..