i see no reason why the chiyuv to be mekarev isn’t a kal v’chomer of Lo Saamod Al Dam Reecha. we see countless times how the neshama is more important than the guf in this regard. the most prominent example would me dying al kiddush hashem. depending on the circumstance on may even be obligated to die for something that isnt yeharag v’al ya’avor. we take this stuff seriously because the neshama is of paramount importance.
therefore…it follows…that if you would not stand idly by and watch someone get run over by a car if you could have done something…then surely you should be mekarev a yid who is slipping or has slipped or has never known better or whatever the situation is.
that being said one is under no obligation to kill themselves or risk their life to save another. so if one feels that one isnt up to kiruv becuase it may damage their neshama in some way then by all means dont. but if you dont because you cant be bothered…then i see no reason why Lo Saamod Al Dam Reecha doesnt apply.