To ban content that might possibly violate their own content policies, social media platforms use the term 'borderline‘. This means categorising content as potentially unwanted (e.g. harmful, inappropriate, etc) and sanctioning legitimate expressions of opinion - hence putting lawful speech in a twilight zone.
Internet companies are conduits through which states can exercise their authority beyond their borders. As Chinese companies such as Huawei become more commercially dominant, they threaten the geopolitical power of the US.