Also realist doesn't mean that he can't be decent guy.
Sure, but risking your life and the lives of your most important servants to save the bratty daughter of a guy who just tried to kill you, for no real benefit, goes beyond "decent". The daughter even participated in the plan of trapping him, so she's no innocent.
The initial plan was justified, he knew he was walking into a trap and planned to use it as a justification to later conquer the territory without drawing more aggression from neighbors. But once the ants came in, there was no longer any need for justification. He could let the ants do the dirty job of dealing with the count, then come in and claim the territory from the ants. Saving the daughter is all risk for no benefit. A realist would at least weigh those against each other.
The count's forces were a match for the forces he had deployed, and he had to resort to subterfuge to escape. But then something stronger than the count's forces appears, and he can just rush into the heart of the enemy forces?