Two points to calm the hysteria:
1) We are at the mercy here of journos, to whom the 'runway' extends from the gate to the far end of the piste.
2) The phone, if unclaimed by pax, should not travel on the flight
Other than that, let's wait and see the facts. I have myself (in BA) offloaded a suspicious package (at LGW, out of the window and into the arms of a member of the fire service who attended the aircraft 'on the runway' (we call it taxyway) and received said (ultimately harmless) item into a secure stowage.)