I don't doubt it. The author, Peter Kovacs, is not a reporter, and rather than a news item, this is an opinion piece. Since Kovacs "was president of NutraSweet Kelco Co. from 1994 to 1997," I'd say he's more than qualified to give his opinion, since ascorbic acid production is also a sugar fermentation process.
From Wikipedia: "China is slowly becoming the major world supplier as its prices undercut those of the US and European manufacturers."
From the article linked to that statement by Wikipedia: "DSM makes last stand against Chinese vitamin C,":
"20/10/2005 - China's dominance of the vitamin C market was confirmed last week as DSM halted all production of the bulk vitamin in the US, making its Dalry plant in Scotland the only remaining major plant outside of Asia."
Four Chinese producers now supply the majority of the global demand for this vitamin, selling at prices well below the numbers that are feasible for and the other remaining European vitamin maker, BASF.
That could be right. I think there are some companies in America that extract natural vitamin C from citrus fruit and sell it in tablet form. But there may not be anyone left making bulk synthetic vitamin C.