Honestly, I also do not understand their wording on that. Getting on board with foreign boycott is not ok that much is clear, but exercising your freedom of affiliation as a company is fine as long as it doesn't contradict US foreign policies. So if you don't want to contradict those you shouldn't boycott them if you don't your gov deciding that your decision is not independent. I mean you never know, but stranger things have happened. Just because of that I generally advise foreign entrepreneurs to think hundreds of times over before they go ahead to open their offices in US.