There’s more to it than just not antagonizing the guards. I mean if you make them mad by doing something that is legal that’s probably not ideal for you practically speaking, but it’s not the end of the world. Destroying evidence while they are investigating you is not just going to make them mad though. It is illegal (18 USC section 1519).

Where I think people are a little confused here is not realizing that this would be equally illegal in many other countries. At least in the UK and France, border investigators also have the power to demand your PIN. And it is also illegal to wipe your phone during an investigation in those countries.