I don't know if you are technically legally right, but it's hard to disagree with your rationale. It certainly makes sense to me.
Doesn't it fall into this Roch.....................Knowledge of the crime
To be convicted of an accessory charge, the accused must generally be proved to have had actual knowledge that a crime was going to be, or had been, committed. Furthermore, there must be proof that the accessory knew that his or her action, or inaction, was helping the criminals commit the crime, or evade detection,
(1) Being an accessory after the fact?
(2) Perverting the course of justice?
any act that interferes with an investigation or causes it to head in the wrong direction may tend to pervert the course of justice.