The decision in this case is correct, but although the opinion is substantially correct, it contains some dangerous language that reflects sloppy thinking on the issues involved.
This can be seen from two quotes:
The power to tax the exercise of a privilege is the power to control or suppress its enjoyment. Magnano Co. v. Hamilton, 292 U.S. 40, 44, 45 S., 54 S.Ct. 599, 601, and cases cited.
A state may not impose a charge for the enjoyment of a right granted by the federal constitution. Thus, it may not exact a license tax for the privilege of carrying on interstate commerce (McGoldrick v. Berwind-White Co., 309 U.S. 33, 56-58, 60 S.Ct. 388, 397, 398, 128 A.L.R. 876).
The dangerous language comes in part from the cited cases, but should have been corrected. The problem lies in treating the terms "right" and "privilege" as synonymous. This has a long history in English law, in which originally all "rights" were considered privileges granted by the sovereign, that is, the monarch. But with independence of the American colonies, making the people the sovereign, and their adoption of the Constitution, came recognition in law that the rights recognized and protected in the Constitution precede the Constitution, and are either natural, preceding society and government, or arise out of the social contract that created the society, and are therefore not "granted" by the Constitution, but only recognized and protected by it, and would exist even if the Constitution did not.
This sloppy thinking can be seen in the second quote, which makes a confused connection between the exercise of the rights to publish and practice religion with engaging in interstate commerce. No government, federal or state, may impose a charge on the exercise of a right, or otherwise legislatively restrict it. That is what "right" means. A right may only be disabled, or restricted, by due process, that is, on an individual case to case basis, either in punishment for a crime, or upon proof beyond a reasonable doubt to a unanimous jury of twelve that if not disabled, the person would cause harm to himself or others.
As for the regulation of interstate commerce, one can find no basis in original understanding that even the federal government, under the commerce clause, has the authority to make it a privilege to engage in such commerce. The power to regulate commerce is the power to impose legislative restrictions on the modality of tangible commodities and the trade in them, item by item, and not on the persons who might engage in such trade.