There were two Charles Pinckney's (1st cousins) from South Carolina at the 1787 Constitutional Convention.
Both were spectacularly successful in life and lived until about 1825.
Both were strong Federalists in 1787, contributing to and helping ratify the new Constitution.
Charles Cotesworth Pinckney was 11 years older, a general in the Revolutionary War and close friend of George Washington, he remained a Federalist all his life, even when Federalists became unpopular in South Carolina.
In 1800 he was nominated for Vice President under John Adams and in both 1804 and 1808 for President on the Federalist ticket, losing all three times.
Charles Pinckney (younger), who you quoted, also served in the Revolutionary War, as a young lieutenant, was captured by the Brits at Charleston in 1780, held, sent north and finally released returning to Charleston in 1783.
After the 1787 Constitutional Convention, younger Pinckney came to side with Jefferson's anti-Administration faction and managed Jefferson's 1800 South Carolina presidential campaign, against his cousin, the elder Pinckney on the Federalist ticket.
Younger Pinckney claimed a lot of credit for writing the Constitution, and he is acknowledged to have inserted the fugitive slave clause into it.
Neither Pinckney cousin is ever quoted as having acknowledged or defended an unlimited "right of secession" at pleasure.
Few did. The right to secede to self-determination in the minds of most patriots, came only after a "long train of abuses and usurpations," and is enshrined in the Constitution.
The same constraint applied to those making the laws:
"Can it be believed, that under the jealousies prevailing against the General Government, at the adoption of the Constitution, the States meant to surrender the authority of preserving order, of enforcing moral duties and restraining vice, within their own territory?... Laws are made for men of ordinary understanding, and should, therefore, be construed by the ordinary rules of common sense. Their meaning is not to be sought for in metaphysical subtleties, which may make anything mean everything or nothing, at pleasure."
[To Justice William Johnson, 1823, Monticello, June 12, 1823, in Thomas Jefferson, "The Writings of Thomas Jefferson Vol 15." Thomas Jefferson Memorial Association, 1903, pp.448-450]
Many, if not most, debates on the constitutionality of this or that law is based on those "metaphysical subtleties" (which can mean anything,) rather than original intent. Those who believe the government has the right to make laws at pleasure are enemies of the Constitution, and the people. The right to self-determination does not exist in the minds of controlling, tyranny-minded individuals, who are the most dangerous of all people.
Mr. Kalamata
And all the states of the Union voted for it.