You are confused again, Sock. Censorship by the federal government is illegal. It violates the 1st amendment. Censorship by a corporation is legal. It is NOT threatening bodily harm.
It certainly can, and does...even legally. See the 16th amendment, for example. 'Tis the season, you know. What do you think happens if you refuse to pay your taxes?
What do you think happens if you murder someone? The crime of murder and it's associated punishment IS a threat. Don't murder people and you won't have a problem.
No.
Bill collectors threaten all the time. If they have legal standing in the State they are collecting for, they can SUE YOU. That's a threat. If a squatter is in your house and you tell them you are going to call the police to enforce their removal, that's a THREAT. It's legal in a lot of States too, including Washington.
If you sign a contract and then decide to breach it, the consequences laid out for doing so in that contract are the THREAT. That's legal (as long as the contract itself is valid under the law).