Except that's not going to happen because evidence spoliation (legal term) is a crime. And that's what he did. You can say it shouldn't be but it is. This is slam dunk and it happens all the time. It's the same crime as destroying evidence that's been subpoenaed or that it has a preservation hold on it.

And the court gets to assume that whatever was on that phone hurts your case, regardless of whether or not it did.

It would've been better if he'd crossed the border with a phone already factory reset and just restore it after entry.