They hint at US opposition in the article but they don't come out with all the history behind it...
"Some opponents of the canal worry that the financing will actually come from the Chinese government itself, which Richard Feinberg, a fellow at the Brookings Institution, describes as "the Chinese planting their flag right in the heart of the Western Hemisphere.""
NPR is a news outlet funded in part by the US government it isn't particularly surprising that they aren't going to delve into history that makes the US look bad.