I think you're chasing your tail here... It has been argued by many with great success that Human Beings inherently do not like to kill or harm each other... Aikido in a Martial Context exploits this...
I am not sure how you see Aikido exploiting that concept martially. I think that people actually do not mind killing that much -- some even get to like it -- some far too much - and that love and killing are not opposites -- at all. Complements, perhaps, but not antitheses.
Read Hillman's introduction
and you may have more sympathy for O Sensei's resort to mythic terms for dealing in love and the killing instinct.