A camera would, presumably, be an electronic device under that rule.
It depends, some cameras are entirely mechanical. Most have a small battery, but then so do digital watches.
Actually in a crash it would decpaitate someone, that's the other reason they insist on them not being used and eveything heavy is supposed to be stowed.
HT is correct, in any accident severe enough that a small camera would "decapitate" you, you would already be dead. Not "everything heavy" is supposed to be stowed. A large book is much heavier than a lightweight camera, and not only do CC not tell you to stow books before landing, they helpfully make an announcement to tell you about the personal reading light above you so that you can keep reading.