Actually, there is a major USA textbook publisher backing a version of SM. HMH publishes Math in Focus, which hews pretty closely to the SM method. I know several private schools, and at least two public schools, which use it. There is a network of math education professors, based in Massachusetts, who publish research and conduct trainings on it, and promote its use (both the Marshall Cavendish and HMH published versions). Both the MC and HMH versions are on the approved curriculum list for California, which pretty much makes them approved everywhere.

So there are no regulatory obstacles to schools using SM.

...pronounced like the long vowel and first letter of the alphabet...