Pure bull manure.
If the 2nd Amendment only applies to regulating militias, then what does he make of Article 1 Section 8 of the Constitution, which gives Congress the authority to organize, arm, train and discipline the militia?
The Second Amendment refers to the armed, unorganized body of the people - a militia in plain usage meaning any one who can take up arms.
Article 1 Section 8 refers to the organized militia one created by Congress. Today called in the states the National Guard but which can be called forth by the federal government.
They are two different forms of militia. The Second Amendment would be redundant if the Founders had meant to set up only a state-organized militia.
Ask a liberal and hoplophobe to explain why two different kinds of militia are referenced in the Constitution.