Though their intentions are honest, there's a couple of problems with the article.
One, jury nullification is a somewhat different creature than the nullification held out by Thomas Jefferson in the Virginia and Kentucky Ordinances and by South Carolina in their famous tiff with Andy Jackson.
Jury nullification is a legitimate power of the people, as is electoral nullification, and as is Militia nullification, a dicier subject which is nevertheless treated as "cartridge-box nullification" and a kind of People's veto over oppressive government policy. See Elaine Scarry's law article on the distribution of power in the Constitution. (Scarry, "War and the Social Contract: Nuclear Policy, Distribution, and The Right to Bear Arms", 139 U. PENN. L. REV. 1257 (1991). Available at http://www.saf.org/LawReviews/Scarry1.html [cold link].)
State nullification has a real problem with the Supremacy Clause of the Constitution. If you want to see a fine exposition of its doctrinal weaknesses, see Jefferson Davis's inaugural speech as President of the provisional Confederate Government in February, 1861, in which he couched his case for the necessity of secession as a function of the doctrinal failure of nullification.
Lastly, government disobedience of the law is a separate phenomenon completely, and needs to be separated from nullification issues and civil-liberty issues and considered as a problem of its own, of simple misfeasance, nonfeasance, or malfeasance of federal officials in the face of federal law.
I must, however, respectfully disagree with the statement State nullification has a real problem with the Supremacy Clause of the Constitution.
There is no conflict if one realizes the clause means what it says and says what it means.
Article 6, Clause 2
This Constitution, and the Laws of the United States which shall be made in Pursuance thereof; and all Treaties made, or which shall be made, under the Authority of the United States, shall be the supreme Law of the Land; and the Judges in every State shall be bound thereby, any Thing in the Constitution or Laws of any State to the Contrary notwithstanding.
Unless laws fall within the powers granted by the Constitution and within the jurisdiction of Constitutional limits, it is NOT made 'in Pursuance thereof'. A State has EVERY right to nullify it, and the People have every authority to ignore it!
That a law limited to such objects as may be authorised by the constitution, would, under the true construction of this clause, be the supreme law of the land; but a law not limited to those objects, or not made pursuant to the constitution, would not be the supreme law of the land, but an act of usurpation, and consequently void.
St. George Tucker View of the Constitution
South Carolina's action concerning tariffs were unconstitutional as the federal government IS given the authority to regulate them, and the State was bound to observe those regulations as long as they were a part of the Compact.
Later actions by the South however are a different kettle of fish, but in an effort to stay on topic, perhaps we should save that argument for another thread. :-)
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In the case of second Amendment, there is no question. It is a specific restraint on the authority of government at both the State and federal level.
The prohibition is general. No clause in the Constitution could by any rule of construction be conceived to give to 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.
A View of the Constitution of the United States, William Rawle.
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IMHO, people give the 'supremecy clause' WAY too much credit. The federal legislature was intended to legislate for federal concerns, NOT to micro-manage the States.
It is distressing to reflect, that it ever should have been made a question, whether the constitution of the United States on the whole face, of which, is seen so much labour to enumerate and define the several objects of federal power, could intend to introduce in the lump, in an indirect manner, and by a forced construction of a few phrases, the vast and multifarious jurisdiction involved in the common law; a law filling so many ample volumes; a law overspreading the entire field of legislation; a law that would sap the foundation of the constitution, as a system of limited, and specified powers.
St. George Tucker Blackstone's Commentaries