He is lying when he says it was voluntarily. From ChatGPT:

The penalties for violating Executive Order 6102 were severe:

	1.	Criminal Penalties: Violation of the order was considered a criminal offense. Those found guilty could face a fine of up to $10,000. This was a substantial amount of money at the time, equivalent to more than $200,000 in today’s dollars, when adjusted for inflation.
	2.	Imprisonment: In addition to or in lieu of fines, violators could be sentenced to imprisonment for up to 10 years.
	3.	Forfeiture of Gold: Any gold not surrendered by the deadline (May 1, 1933) could be confiscated by the government without compensation. The government would seize gold that had been illegally retained by individuals or businesses.