I don't get this.
My level of paranoia is such that I cannot sleep in a room with the door open or for which the door cannot be locked. Even if it is locked, I put something behind it that causes noise. I have door and window sensors that send alerts. I can't have a ground floor bedroom.
And through all of this, the LAST thing I'm worried about is some joker finding my phone and, of all things, using it to come to my house. First off, if they found the phone they'd probably be trying to sell it and second, my phone never leaves my sight anyway. But let's assume that it were left somewhere. If they managed to get past the PIN, they might very well use the location to find me to return the phone. As someone else said I'd be more concerned with them flipping through my email than anything else.