Commerce Clause dicta in NFIB?

One open question following NFIB was whether the discussion of Commerce and Necessary & Proper in the Chief Justice's opinion was dicta. If he declared the law valid under the Taxing Clause, was it essential to the judgment that it was not valid under other constitutional powers?

In a part of the opinion not reproduced in the book, the Chief argued that the Commerce analysis was necessary and not dicta. The Chief wrote the following:

The statute reads more naturally as a command to buy insurance than as a tax, and I would uphold it as a command if the Constitution allowed it. It is only because the Commerce Clause does not authorize such a command that it is necessary to reach the taxing power question. And it is only because we have a duty to construe a statute to save it, if fairly possible, that §5000A can be interpreted as a tax. Without deciding the Commerce Clause question, I would find no basis to adopt such a saving construction. 

A "saving construction" is a judicial interpretation that "saves" the law from its constitutional defects. But a court should adopt a saving construction only if the law is constitutionally defective--which can only be determined by first analyzing the law in its natural reading under the natural provision. Constitutional invalidity comes before the saving construction which comes before the Taxing Clause analysis--therefore the Commerce analysis, to determine invalidity, was necessary.

But compare this with Heart of Atlanta. One could argue that the public-accommodations law in the Civil Rights Act reads "more naturally as a command" to accord equal protection to all persons under the Fourteenth Amendment. Yet the Court did not start by analyzing Title II under the Fourteenth Amendment, find it invalid because of the state-action requirement, and then use the Commerce Clause as a last resort. It proceeded directly to the Commerce Clause, recognizing that the fact that Congress was trying to stop a moral and social wrong did not Congress could also act against that wrong when it obstructed interstate commerce.

If Roberts is correct, then the Heart of Atlanta Court arguably was obligated to say something like this (this is a riff off the NFIB language, quoted above):

The statute reads more naturally as [a way to ensure the Equal Protection of Laws] than as a [regulation of commerce among the several states] and I would uphold it as a way to ensure Equal Protection if the Constitutional allowed it. It is only because [§ 5 of the Fourteenth Amendment] does not authorize such a [law] that it is necessary to reach the [Commerce] power question. And it is only because we have a duty to construe a statute to save it, if fairly possible, that [Title II] can be interpreted as a regulation of [commerce]. Without deciding the [§ 5] question, I would find no basis to adopt such a saving construction.

Consider these two distinct approaches to how Congress can enact a law under multiple powers and how courts should review those laws.