Dishonest signalling isn’t worth it. By dishonest signalling, I mean enaging in a signalling behaviour when you don’t possess the quality you wish others to think you have. A weak peacock who grows a conspicuous tale will be eaten by predators. A stupid person who tries to get a degree in classics will fail his subjects. Faking the moon landing carries the risk that the conspiracy will be exposed and the American government would become a laughing stock. A good way of remembering this criterion is the slogan "You can't signal to rubes."

This seems false as a generalization.

Suppose that a double agent's loyalty is in question, so they choose to turn a sympathizer of their own country in to the government. Turning in a sympathizer of their country is certainly something that a person loyal to that country would have reason to be reluctant to do. It's likely to decrease suspicion that they're a double agent. But if it allows them to continue passing valuable information to their country, and to avoid being caught and punished themself, then it's probably worth it.

I don't know what it would make sense to call such behavior if not signalling, and dishonest signalling at that.