Here Mason was arguing against those who believed that the bills of rights in each of the states would protect against federal laws that encroached upon rights protected in the state constitutions. Mason was saying that a federal bill of rights was necessary because, for example, a provision in a state constitution that guaranteed the right of the people to free speech would not protect against a federal law that infringed on the right of free speech...because federal law (the law of the general government) is paramount to the constitutions of the states.
No question that many, maybe even most, of the drafters of the Constitution and state legislators believed that there are certain natural rights upon which no government can infringe. But ratification of the Constitution was ultimately a political battle and there is no way that most of the state legislators would have been willing to allow the new federal government to dictate to their state legislatures what the scope of these rights are...and there is no way the Federalists would have risked a revolt against the Constititution during the battle over ratification by suggesting that is what they intended the new government to do.
And if you keep reading his works, and those of the other Founders, they didn't want the State infringing any of those Rights either. Hence statements from them like:
"The whole of the Bill [of Rights] is a declaration of the right of the people at large or considered as individuals … It establishes some rights of the individual as unalienable and which consequently, no majority has a right to deprive them of." Albert Gallatin to the New York Historical Society, October 7, 1789
The prohibition is general. No clause in the constitution could by any rule of construction be conceived to give congress a power to disarm the people. Such a flagitious attempt could only be made under some general pretence by a state legislature. But if in any blind pursuit of inordinate power, either should attempt it, this amendment may be appealed to as a restraint on both. William Rawle 1829.
"It had become an universal and almost uncontroverted position in the several States, that the purposes of society do not require a surrender of all our rights to our ordinary governors; that there are certain portions of right not necessary to enable them to carry on an effective government, and which experience has nevertheless proved they will be constantly encroaching on, if submitted to them; that there are also certain fences which experience has proved peculiarly efficacious against wrong, and rarely obstructive of right, which yet the governing powers have ever shown a disposition to weaken and remove. Of the first kind, for instance, is freedom of religion; of the second, trial by jury, habeas corpus laws, free presses." --Thomas Jefferson to Noah Webster, 1790. ME 8:112
The United States guarantee to every state in the union a separate republican form of government. From thence it follows, that any man or body of men, however rich or powerful, who shall make an alteration in the form of government of any state, whereby the powers thereof shall be attempted to be taken out of the hands of the people at large, will stand guilty of high treason; or should a foreign power seduce or over-awe the people of any state, so as to cause them to vest in the families of any ambitious citizens or foreigners the powers of hereditary governors, whether as Kings or Nobles, that such investment of powers would be void in itself, and every person attempting to execute them would also be guilty of treason. Tench Coxe. 1787. An Examination of the Constitution of the United States of America
The only way the Federalists got their Constitution at all was because of the Primacy of the Bill of Rights as "Supreme law of the Land". This isn't about the Feds dictating to the States or vice versa. This is We the People telling them both "hands off our we'll kill you."