Bhagavan is Antaryami.
What does that mean?
He controls everyone and everything from within.
Just as he is omnipresent, he is everywhere; he is inside also.
So he should be inside Kamsa.
So why didn't Bhagavan destroy Kamsa and his associates from within itself?
Why did he have to kill them physically, externally?
The world operates in certain ways.
Bhagavan has only set the ways in which the world operates.
It is his system.
Why would he violate his own system?
In the world, there are rules.
Take a can of petrol, pour it over something, and set fire with a matchstick.
It will burn down.
The fire, power to burn is in petrol, it is inside petrol.
But merely by pouring petrol over something, it doesn't burn.
The stimulus has to come in the form of a burning matchstick.
Then only the power of petrol to burn is released.
In the same way, even if Bhagavan is inside Kamsa, he would wait to be triggered by his own Krishnavatara which is external, external to Kamsa.
Because it is not just destroying evil, there is so much more involved.
The whole episode is a teaching to the whole world.
So much to learn - what is evil, evil will not survive for long, power of Bhagavan, role of Bhagavan - so much to learn.
This learning can happen only when it is visible, perceivable to everyone.
Bhagavan does everything visibly so that everyone can learn from it.
Utilizing money that is impure makes you more and more attached to the world. You become more and more addicted to pleasures and enjoyments.
In situations like saving an innocent life, during a marriage, to protect family honor, or in humorous teasing, speaking untruth is not considered wrong. Wise people say such falsehood does not break dharma. Speaking untruth for a good purpose, like protecting dharma, is not sinful.