Going "off the grid" (from your perspective) can look to others like "disappeared, and possibly dead". The photo sharing part could be useful for them to grieve, and you probably wouldn't enable this feature if you didn't consider them.

On the other hand, being kidnapped for ransom or being kidnapped by the state (i.e., arrested) is a far more serious false positive, I would think, because deleting your digital data would probably make recovering a whole lot harder.