ObamaCare coerces Americans into health insurance contracts on threat of a financial penalty, which Justice Roberts now speciously calls a tax in order to find some penumbra in the constitution other than the commerce clause to allow it.
Under contract law, coercion nullifies any contract when it nullifies the equality which must exist between the two parties making the contract.
Justice Roberts pretends that there is equality here. There isn't. I either buy a policy on my own, or pay a fine to the government. Either way, I'm out the money and have no choice about it.
In the real world, choice means I get to choose not to purchase and keep my money. In the case of ObamaCare, I have no such choice.
And therefore health insurance will stop being a lawful contract.
Justice Roberts has just vitiated centuries of contract law. You can call that anything you want (tyranny comes to mind), but it certainly isn't conservatism or originalism.