Pair with the malicious device, and then what...? They'll have my address book??? Big deal. I agree it's a security issue, but, there it not much they can do, now, is there?
Also, Bluetooth has a maximum range of 30 feet. My neighbors don't even KNOW what Bluetooth is. If a malicious person wants to mess up my Bluetooth connection, he'd have to do while I'm driving... and only if I am trying to pair my phone as I'm driving.
It just doesn't seem very plausible.
Juan