That's correct, but with ASE only engaged (ie no AFCS modes) the parallel actuators still operate and extend ASE authority to 100%. Although slow compared with the series actuators, they are certainly fast enough to give problems on the ground if the ASE is malfunctioning or misused.
Maybe this isn't the case with the new system. The SEP20 has a manual trim mode which takes out the parallel actuators but, as far as I know, it's never used except during initial flying control demo sorties.