Why have the king's men been described as practical? What is ironical about this description?

The king's men were considered to be practical because they knew their king was not equipped with the mental faculties to be a king and they were aware of ways to manipulate him. This pragmatism of the king's men is ironic because in spite of the fact that they were being honest, they were insidiously working in a way to ultimately put the blame on the king. Knowing well about the king's sense of justice, they saw to it that the plan worked in such a way that they could all extricate themselves from the tricky mess. Ultimately leading to the self-imposed execution of the king and a descent to anarchy for the state.