Yep, in parts of Europe lens-theft is huge concern, many lenses cost more than the camera-bodies they mount to. When approached by strangers, I have always twisted the camera-strap to place the lens against my chest. Another ploy, is a local claiming you are photographing in forbidden areas and demanding you relinquish the camera...so they can remove the film and/or data card.
This happened to me in Turkey, I refused...(kinda risky, because I was completely alone.)...and said I would only comply if the request was made by a uniformed-officer.
The tip for the image-stabilizer looks to be a good one...I'm going to try that one, Been trying for migrating-Geese shots with a monopod that has the 2 lower extentions are spring-locked...tends to collapse at the moment of the shot.