I’m pretty certain that “speech” means expression of ideas, not the audible act of speaking. So making a threat is not covered in the same way that perjury isn’t covered.
Isn't actual speech also an expression of an idea?
But yes, another good example would be perjury.
I think GP is saying that threats or perjury are not just characterized by the expression of an idea but another underlying crime. Like if someone walks into a bank and says "give me all your money or else", it's still a crime, the speaking part of it is immaterial.
I wish I had expressed it as clearly: very much this.