Hey Chris,
The correct way on kernel panic, before powering off, would be to use the Magic SysRequest keycodes for sync (flushing caches to disk), umount filesystems, and poweroff.
However the bug with controller rebooting after shutdown because backfed by display power over the USB Port is a very short boot - the power backfed from display is too low to supply a complete boot procedure
You can prevent backfeeding power over USB this way: