Why would a 1 bleed inop call for the associated pack to be switched off in the operational procedure. When the associated pack is working fine.
Could it be an error in the MEL ?
Not completely familiar with the 320 bleed/environmental system. I would suspect that 2 packs on one engine bleed at idle could require excessive air demand at idle engine air supply volume/pressure. Most modern ACM's have "laberynth" or air bearings, ops at low speed could damage them. But still just speculation.
Not sure what an LMV is, may have a 320 tech around to answer that, i am sure you could find an answer on the eng/tech board.