I don't think the crime of destroying evidence / tampering with evidence depends on what your status in custody is. If the police knock on your front door and you start shredding documents, that's still a crime.
Now, could that get tossed about because they denied him access to a lawyer? Maybe, I don't know about that part.
Now, could that get tossed about because they denied him access to a lawyer? Maybe, I don't know about that part.