Advertisers on cable can't be local car dealers and the rest; it's the nature of cable after all. This leaves national US companies, and most of those have global operations and must tread carefully.

Here's an example: Carlson is calling for an invasion of Canada. Think advertisers with business there don't see a potential risk with advertising on his show? They're one grassroots movement away from having to vouch they'll stop advertising on his show. Better to steer clear anyway.