Thanks for the info. I hadn't given the locking mechanism much thought. I'm generally in "safe" areas, but I suppose if I parked my car and went on a 2-3 hour ride, that'd be plenty of time for someone to yank the bars.
So the OEM bike mount then has no security for locking the bike down either? That's a deal breaker then because theres no way I'm leaving my bike on my roof if I want to stop at a store or restaurant while I have it with me.