Plan Istiana (Mount & Blade 2: Bannerlord)

In General, passing storyline, I have fulfilled all the conditions came to pocico and we decided to destroy the Empire... it's All good, I created the Kingdom, but then there is a second quest - the plan Istiana she allegedly learned that I want to destroy the Empire and is preparing some kind of conspiracy... in Fact, the quest tells me once to prevent this conspiracy
Does anyone even understand the point of the quest? I don't