Oh, please. Why would he do that? What on earth does Roberts have to lose by defying the president and a senator?
Nothing, that's what. He's got a life-long gig, and it's almost impossible to remove him from it. He has no reason why he should give any kind of a crap what anyone thinks. They can't touch him.
A judges job is not to "protect minorities from tyranny." It is to determine whether something is within the legal framework of the country. Believe it or not, our framework is not bulletproof. There is plenty of legally feasible tyranny that is possible (although I wouldn't agree with you that this is any such case).
Now, if you're unhappy about the state of the law, if you believe said law allows tyranny, that is what the legislative branch is for.
OK let's discuss constitutionality then. The SCOTUS does not make law, they simply evaluate law as to whether it conforms to the constitution, or not. It is NOT "judicial activism" to declare a law, or lower court ruling based on a law, as unconstitional, no matter how popular it may be. Justice Roberts wrote a "majority" opinion that NO other justice, even those voting for making the PPACA law stand (based on the commerce clause, that he asserted was WRONG), would sign on to. That makes the majority opinion, in effect, only his; is that NOT judicial activism of the highest order? For a federal law to be constitutional it MUST be based on a power ACTUALLY granted to the federal gov't by the constitution.
Justice Roberts claimed that since IRS was involved, IN A MINOR WAY with the individual mandate (a penalty for NOT engaging in commerce, by spending income on medical care insurance), that it was not unconstitutional. A very bad legal decision, IMHO, as it ignores the REAL issue, which is the federal gov't requiring a citizen to either purchase a PRIVATE good or service, that has NO basis on any federal power granted by the constitution AT ALL, or to be assessed a penalty (or added tax).
The federal power to tax INCOME (IRS) comes only from the 16th amendment, that simply allows INCOME from all sources to be taxed. IMHO, Roberts has, in fact, become an "activist" judge in allowing HOW INCOME WAS SPENT, rather that simply the income itself, to be subjected to enequal consideration for purposes of taxation. Two citizens both making EXACTLY $50K in income (from any source) should not be taxed any more, or less, than the other, based on the 14th amendment requiring EQUAL protection under the law.
The bulk of our 80,000+ pages of FIT law is addressing how income was spent with its MANY credits, deductions and exclusions, so is NOT based on the income from all sources, but rather on how that income was LATER spent, and is therefore unconstitutional. The SCOTUS is far too lenient in giving even a slight INDIRECT relationship to a federally authorized power (e.g. taxation), to serve as a reason to say that a law is constitutional. Simply using the IRS as a collection agency does NOT make the PPACA fine/penalty LEGAL, as NOTHING in the constitution gives the federal gov't power to order a citizen to buy a private product or service, to reward them for doing so or to punish them for not doing so.