Scenario#1 - 
Player A (me) turrets a wirble.  Said wirble drives around aimlessy, pleading for someone to bring him supplies.  Meanwhile, Player B in a B-25, lumbers in and delivers the coupe de grace.  Player B did more overall damage but was only able to do so because the wirble was already neutered.  Player A deserves the kill IMO.
Scenario#2 -
Player A turrets a wirble.  Said wirble runs back to spawn point to get a ditch.  Player B (me) drops a bomb on him for the kill.  Player B did this unopposed because Player A did the real damage and deserves the kill.
In Scenario#1, I should have got the kill but not in Scenario#2.  The kill credit should have been reversed in each scenario.