This argument has been repeated so much, I'm going to try to explain. I'm not a lawyer, but this is what
I learned in school in the US. There are numerous examples of voluntarily giving up your right to free speech. In the United States there are criminal and civil suits. You won't be criminally charged by the government for your free speech about CPU benchmarks, but if you actually agreed as part of a contract to not disclose benchmarks in order to get something, then you can be successfully sued by an organization or individual in a civil suit. They can't throw you in jail but they can take your money.
I highly suspect the same thing is true in most first world countries, otherwise a lot of companies wouldn't be able to do business because it would be illegal to keep trade secrets. What did they tell you in school?