The zinc majority penny has been more valuable than 1c several times since it was introduced. It was a big story in 2005/2006 as zinc prices surged. Yet there wasn’t large scale arbitrage of this in large part because it was illegal and comes with hefty fines.

It’s also due to the difference not being worth the effort most of the time but that doesn’t change the refutation of the claim that no pegs work. The penny peg works even in a world where the actual utility of a 1/100th usd coin is probably negative.

FWIW You can't conterfeit coins, but you can deface them as I understand it. They're not protected - just currency (folding money).

This is generally true, but I think you might be out of date. About 15 years ago, the US government passed a law that specifically prohibited the melting of pennies and nickels for the purpose of selling the materials for profit:

§ 82.1 Prohibitions. Except as specifically authorized by the Secretary of the Treasury (or designee) or as otherwise provided in this part, no person shall export, melt, or treat: (a) Any 5-cent coin of the United States; or (b) Any one-cent coin of the United States.

https://www.law.cornell.edu/cfr/text/31/82.1.

Click "next" on that link for the special exceptions, which do allow for modifying small amounts of these for jewelry or decoration.