anti theft pin
When your phone is switched off why cant it ask for the pin before it switches off, the first thing a thief does if snatched while you are using it is switch it off.
This has been discussed numerous times here. This feature will do nothing to prevent thefts.
Thieves do not care if your phone is on when they take it.
Not one bit. It will do nothing but frustrate and annoy the vast majority of users who do not have their phones stolen or lose them.