The only real chance for ambassador to be good here would be to thin the deck for a torturer chain. The silk road player would have to hope to pile out the silkroads and estates and accept taking all the curses. The torturer player will probably need to pick up a couple silkroads for denial purposes and pick up 4-5 provinces before that happens. It's tough for me to say offhand which strategy is dominant, but it would promise to be an interesting game.
I just don't see a Torturer chain as a plausable scenario. In order to win, the Torturer player needs to pick up SR, a good many Provinces, and do it
fast. Because, if the SR player can empty the SR and Estates (which he is likely to do quite rapidly, despite the Torturers) then the game will be over before the Torturer player can pick up enough VP for a win. Also, if they start to pick up Torturers, you can pick up Ambassadors and send the Curses right back to them.