It absolutely is the responsibility of American businessmen, but the question wasn't about businessmen it was about the NBA - the NBA is a corporation with no fealty, loyalty or citizenship within any country in the world. I think in America there has been a hard push to prevent government control into various companies - just because this scenario is about decrying a foreign entity instead of the US flexing power domestically (i.e. via warrantless wiretapping) doesn't change the fact that, at a basic level, it's the same exact problem.
Lastly, there are no American corporations, nothing should be given to them because they're assumed to be American and nothing should be expected of them - anything required of them should be encoded into law so that one corporation can't exploit the morally correct decision of another corporation as a weakness.