he did kind of answer why mobiles are not allowed to be left on at all times on the aircraft, he just forgot to mention the bit about refueling...
Which bit about refueling? If it's the myth about cellphones triggering explosions, then I'd have to ask why tarmac radios at several more watts and considerably less distance don't get pinged. Besides, in my experience most tarmac fuel trucks seem to come equipped with a very handy cellphone and a radio ... and there's nothing special about the phone, just a regular old Nokia.
Mind you, I don't want anyone wandering about a busy tarmac yabbering into and totally distracted by the phone stuck to their ear. However, when it's patently obvious that they don't make fuel trucks and parked aircraft explode, it'd also be nice to not have to tell porkies to enforce a quite reasonable rule.