I guess the same reason if you turn the key on a normal setup but don't quite start the engine you have to switch off before having another try ...to stop you engaging the starter while the engine is already running
K
Interestingly on the newplus six and newplus four you have to turn the key then press the start button once and then press the start button again to actually start. Whereas on my Mog you turn they key and then press the start button and away you go !
