Yes, that's my defense. If the Secretary of State replaces her blackberry and gives the old one to her aid to dispose of, she doesn't have to know what exactly that person does.
And again, you might be right. The problem is "might" don't cut it. You need to be able to prove it "beyond a reasonable doubt." And it was destroyed as part of a procedure to protect the information on it is plausible from a national security perspective.
I doubt you have a problem when that "beyond a reasonable doubt" standard is applied to Trump. The difference being that in Trump's case, going by what is in the indictment. It will be hard to reasonably claim that Trump didn't take, keep, and tried to hide national security information.