The First Amendment of the U.S. Constitution protects against U.S. laws abridging the right to free speech (this includes regulations). It can include private actors acting for the government, including where an industry is heavily regulated by the government (e.g. radio, and t.v.). A pledge volunarily entered into, and suggested by Steve is not a violation, nor is the request, even if enforced, that people refrain from political speech on the chip board.
I am not saying what is right or wrong, just that the first amendment has nothing to do with this discussion.
Michael Siskin