DS, I think we can all agree that not commanding reverse on the inop engine avoids putting it into the higher thrust mode of reverse idle and you will thereby stop a bit shorter.
Against that we have to consider the major extra runway required by inadvertently:
- not idling both TLs
- selecting reverse on the reverse inop engine instead of the engine with operative reverse.
The choice is between accepting a minor expected degradation or incurring the risk of a surprise serious degradation in decelleration.