ShotOne, if you have a propriety interest in the design of the side stick mounting (there, is that an acceptable enough term for you?) then I'm sorry to have upset you by calling it a shelf. The point is that the loose object in question (with or without a strap) was somehow placed upon it in order that the subsequent events could occur.
If it can happen once it can happen again, even if this was the only time ever in your squillions of hours of operation that anything at all was placed on the side stick 'mounting' (with or without a strap). There, is that bland enough for you?