If only one setting is possible it needs to be high enough to allow for older batteries which are not maintained well.
Back when I worked at a motorcycle shop we sold a lot of batteries because of abuse, mostly when people parked the bike for winter doing none of the recommended storage procedures including disconnecting and/or float-charging the battery. Also with their batteries so small, it doesn't take much sulphation or normal wear to leave it unable to start a cold bike. So for most sport bikes, a 12.2V cutoff is probably pushing it as far as you can go while touring bikes with larger batteries might be able to go a bit lower.
In all honesty, if you want parking mode protection on a bike for more than a half-hour or so, I would highly recommend using a powerbank based source.
Phil