This supports my contention that it is proper to pray for one's enemies' demise, if I am interpreting it correctly.
Correct, in that it is based on varying situations.
On one hand, the same David refused to pray for Absalom's death, and he begrudgingly sent his forces against him.
OTOH, Christ says to pray your enemies and do good to those that spitefully use you. Paul says to oversome evil with good, that you heap coals of fire upon their head (Paul was being positive).
But at the same time, two people died before Peter when they lied. And Peter told Simon Magus to take his simonry and go to hell, so to speak.
It's based on the circumstances. It's not situational ethics; it depends upon factors that are brought up in each case, sort of like a judge being stricter to the man that deficates in his courtroom and more lenient to the guy that controls his bowles.