The pen is mightier than the USB

I read a post in Lifehacker about someone that attached a Disk-On-Key to his child's neck in case the kid got lost:
"My little redheaded boy was SCREAMING for his mom. The 'finder' came to help him, the boy showed the 'finder' the labelled USB drive, the 'finder' then brought him to security, security plugged the USB drive in to his computer, saw the message and called me on my cellphone. When we went to retrieve our boy the security guard asked for our USB drive with the secret phrase on it. The USB drives performed just as set up to. It had my cellphone number, my boys' first name (first name only!) to calm him down and his favorite treat."

I can think of several reason for this "method" to fail:
1) The security could have been clueless about using a USB device.
2) Plugging an external USB device could have been forbidden/disabled due to security reasons.
3) The "autorun" feature could have been disabled.

On the other hand, wouldn't it be simpler to simply attach a written note to the kid?
Digital is not always better than analog.