Surely the only way to ensure that "miniscule risk" of battery explosion is to ensure that all electronic devices (that have that same or similar battery in them) remain switched off for the entire duration of the flight. There is no difference in risk of explosion from the battery whilst below 10k ft or above (or at whatever point your particular airline allows the use of devices to begin again).
Whilst I appreciate you don't make the rules, but have to enforce them, it is this kind of mis-informed rule making/enforcement that drives me crazy.....
Also, since many airlines allow the use of iPad's and other similar devices on the Flight Deck (often at all stages of flight), it would seem that applying this rule for the PAX/SLF is slightly two-faced (again I appreciate you don't make the rules but have to apply them!)
