In the end, Branden truly didn't receive permission to do some spy work and collect intel. Still, that kind of thing was only obvious considering his position and how many envied him.
At that point in time, it should be obvious that all of the noble houses had spies who worked in the territory of their adversaries. If the king didn't know that, he was more stupid than Rain had assumed. Perhaps staying hidden in his castle made him lose some brain cells.
"Your Majesty, I won't deny that I had some people working for me to gather such information, but I was only trying to find those who tried to stop the peace talks with the magic people," Branden explained. "They used anti-magic bombs against my subordinates. That kind of tool is extremely dangerous and can engulf our country in the chaos of war once again."
"I am well aware of that substance; we decided to make use of it to enhance our defenses and for the sake of the future," The king declared.
