It was not still stuck. After power cycle I I rode it home 6 miles cautiously, slowly. I have not managed to reproduce.
At home on the bench I practiced remote disconnect, tinfoil for faraday cage and moving a few meters away. the disconnects behave well, I did 20 of htem. after the 1000ms delay the motors go 0 current as configured. I opened the remote and checked all the solder points / wires inside… they all seemed good. I wiggled them all while moving the throttle and no cutouts.
Still todo, remove enclosure and checking internal connections, then checking failure modes for receiver disconnect, ble disconnect, and can disconnect.