In Holland, Santa, or “Sinterklaas,” as he’s known to the Dutch, doesn't have reindeer or elves; he has a little helper named Zwarte Piet, literally Black Pete, who charms children with pepernoten cookies and a kooky demeanor while horrifying foreign visitors with his resemblance to Little Black Sambo. Each year, on Dec. 5, the morning before the feast of St. Nicholas, children all over the country wake up excited for gifts and candy while thousands of adults go to their mirrors to apply brown paint and red lips. In their Zwarte Piet costumes, they fill central Amsterdam and small village streets, ushering in the arrival of Sinterklaas who, in the Dutch tradition, rides a flying white horse.
To be honest, I chuckled @ that one sign saying racisme in the back.
But if this helper to Santa is doing this against his will, then yes he's a slave. If he wants to do it, but is not getting paid for it, he's a volunteer. If he IS getting paid for it, he's an employee.