I disagree. Telling people to commit a crime such as arson is not protected speech. In my opinion. It is like yelling fire in a theatre as they say.
Please see Brandenburg v. Ohio. The speech must intend to produce imminent lawless behavior. If someone is leading a group of thugs with torches down a suburban street and says, "Let's burn it down!" there might be imminent lawless behavior, but the fact that no one immediately acted upon her speech means the temporal condition has failed.