Would it not be better to have a procedure that calls for both throttle levers being retarded to idle with reverse thrust being commanded on both throttle levers at pilot discretion provided there is not a known reverser fault?
After TAM3054 at Sao Paulo, that's exactly the procedure. If at least one thrust reverser works, both thrust levers are moved to the reverse detent. Although this is really to ensure ground spoiler deployment, any reverse thrust helps with stopping distance on a wet runway.