Yea, that’s not how it works in practice. If they catch you standing over a dead body holding the murder weapon. Then you can’t just say they can’t prove intent if you keep your mouth shut.

Yea but that's where "reasonable suspicion" comes in a court of law. If you are standing next to a dead body, with a bloody knife in your hand.

And doing anything non-standard with your phone is going to shift the reasonable suspicion away from favoring you unless you can explain yourself.

That’s good advice to not talk, but it won’t necessarily save you.