I could see a theif not noticing the tiny lock,jumping on your bike,and then riding away only to tear up your drive train. Better to add a streamer or maybe a thin cable run around the seatstay.

Actually,you're really better off doing a proper lock-up. It drives me nuts when I see people freelock their bikes. Reminds me of the people who have to have the parking spot by the mall entrance because they don't want to walk a few yards. Take the time to lock it proper and it will be there when you get back.