Are you referring to the first amendment? If so, this allows you to speak against the government. It doesn't prevent you from entering optional contracts.

I'm not making any statement about the morality, just that this is not a 1a issue.

I can understand defamation, but it's hard for me to understand disparagement. If i sign one of those contracts with Coca-Cola and later on I publicly announce that a can of Coca-Cola contains too much sugar. Am I in breach of contract?

Non disparagement clauses are in so so many different employment contracts. It's pretty clear you're not a lawyer though.

It is also clear that you can read, since i wrote it.

If the constitution protected you from this sort of thing then there'd be no such thing as "trade secret" laws.