I didn't think Toranaga was going to go meekly, but then when he was being so stubborn with Hiromatsu and allowed him to commit Seppukku, I started to think he was going to surrender in Osaka after all. To actually take his own life as a part of the plan was both nuts and typical.
Sticking the church next to the Brothel was a proper "fuck you" statement. Mind you, the most frequent visitors will likely be the Catholic Priests