It’s a subject of debate. CBP stated it was possession of CSAM. Defendant claims it’s a pretext and that CBP was really investigating his ties with the Defend the Atlanta Forest movement.
But it doesn’t really matter in this case. You cannot interfere with a lawful investigation, full stop. It’s not clear to me that even if the search was unlawful that the defendant will be held not guilty of the underlying tampering/destruction charge, since we already have a mechanism to suppress evidence obtained unlawfully.