The slave was left in charge in boss' absence. He imagined that the boss is not coming back, and started to abuse his position. The boss shall come back and punish the bad slave.
OK, now bring it one level higher. The boss becomes God, the slave left in authority is a ruler, and the other slaves he abused are poor people, widows and orphans. The ruler thinks that God, after giving him authority, is not coming back to demand an account. The ruler is mistaken.
Now, even the "lower" interpretation is not too bad. The bad slave had it coming. The higher is quite good. Do you have any objections?
(This will be my last attempt to explain my interpretation. If this does not get through, nothing will.)