It looks like there are a lot of issues here on the government side, but it also appears like the protestor intentionally gave them a password that, when used, wipes the phone? That seems like a clear example of destruction of evidence.
Why do you think reporters would rather eat a contempt charge vs throwing their sources to the wolves?
Technically that means the cops destroyed the evidence. Their investigatory department should be savvy enough to avoid destroying evidence.
You do not have to give them your pin, by law. They can use biometrics to open your device, which is why you should not use biometrics for device unlocking.
GraphenOS has a couple of settings, a distress pin that wipes the device, and a number of failed attempts that will wipe the device. If the person handed over their "pin", they didn't need to
> That seems like a clear example of destruction of evidence
If he was under arrest, sure. The cops claiming this was a routine airport inspection would seem to muddy the waters, at least.