Isn’t the relevant bit whether you think you’re doing crimes and/or being investigated?
If I’m shredding while the cops knock on my door because they’re looking for a missing cat, that’s obviously not criminal. (I guess the more-pertinent comparison would be they knock on my door and then I put stuff in the shredder while I check around my home.)
Deletion to protect privacy does not prove deletion to prevent apprehension.
I could believe that everything is wholly innocent, but wish to protect privacy regardless.
They can prosecute him (and probably will) but he's got a pretty strong civil rights claim against the federal government for a false arrest and illegal search and seizure.
You can't arrest someone without a warrant or a reasonable suspicion of a crime. These thugs had neither when they arrested him, just that he's "a terrorist". That's why they were trying to get him to confess or commit a crime. That's why they didn't want a lawyer to get involved.