The statement is but an option, of course you couldn't handle your phone handcuffed, that would be extremely difficult.

It's merely a countermeasure prior to any altercations with officers, most phones automatically restarts if you press the power button for a few seconds.

I don't think having to resort to such things is cool, but I indeed had to do this once .

Where I live cops often unlawfully search you and check whatever they want. I was stopped at a traffic light, on the guise of a "drugs operation". Told the officer I'd pick my license and car register, picked those and restarted my phone in 5 seconds. Got out of the car, they searched and soon released me.

In this case nothing happend, but if you're somewhere where cops search unlawfully, and you were not stopped near an alleyway that cops can beat your password out of you with a wrench, I'd totally say you should restart your phone.