Well, this could actually not be a bad thing. Seemed like their relationship would be deteriorating anyways since they were selling to demons. And even though demons were open to a non-aggression pact with the kingdom, that only allows for one contry to eventually betray the other (demons would do it eventually once land became an issue, humans would do it by covertly sabotage demons ability to fight back).
No. 6 also does not give 2 shits about any of their sides as well. He is only thede to set the ground work for his organization in the first place. So causing a 3 way war would reduce a significant amount of combat power which could complicate the invasion.
And he must be loadedd with points by now. Bet he can buy something nice to fight whomever he wants. And with the Prince becoming seemingly impotent (thanks to a certain someone's stray curse), their honeypot plan went to shit. Not to mention Snow actually wanted to jump ship to become a professional gold digger.
So it ended in the best way possible for No. 6. Way easier to earn atrocity points in war because now everyone is a potential target, and at a larger scale too.