I thought about that too, but dismissed it on the grounds that the Aluminium vapour created would condense on the tube walls when it cooled and render them too conductive to allow for re-ignition.
Rossi might get around the Aluminium vapour issue by preprocessing the nickel electrodes in an off line process as Rossi does with the fuel, The LENR active agent would be deposited on the surface of the nickel electrode with little aluminum being added to that surface. Piantelli does this sort of surface/fuel preparation process when he prepares his nickel rods. From what I have seen in the SEM micrographs of ME356 fuel particles, those particles are LENR active after a long fuel prep process where the LENR active agent pops out of the fuel hydride particles and moves around on the supporting carbon substrate producing transmutations in that substrate.
Those LENR active agents might form those balls of light that float around the reaction chamber when energized by the RF signal.