"who is just who is not just is determined by what side you are on"

No, there are absolutes.
We have the Law Of Armed Conflict.
Some weapons are proscribed.
Civilians must not be targeted.
Civilian casualties must be avoided, or at least minimised.

By killing OBL, the atrocities he was planning may have been prevented.
The LOAC would require that civilian casualties incurred in the action be proportionate to the importance of the target.

The undropped 2000 pound bomb would have been considered proportionate.
You may disagree Jim, but LOAC is the fruit of years of debate by the greatest minds, and has been the greatest humanitarian achievement of the 20th Century.

No doubt you could come up with something better, but this is what we have