The anti-Juggernaut “coalition” (as such) is two units down now from what they could build? That won’t get it done.
Sorry none of my advice could help you much-I’ve been in games full of stubborn people like that, and it isn’t fun (to be honest I’ve stuck to my guns too on a few occasions-sometimes you have to just follow through on a threat to throw the game to a third player just to give the guy who stabbed you the hardest time imaginable).
Well, it was too late a couple years ago in game time. Austria has confirmed that he is metagaming with Russia to appear as more valuable allies in future games. 
What’s the appropriate way to deal with that? I can’t think of anything I could do, and I’m not sure there is anything.
That’s complete and utter shite then (tho I suspected such several turns ago), and completely against the spirit of the game. The way to deal with it is to deep-six this gang of metagaming bozos and try some anonymous press games, where you don’t know who is who and that kind of crap can’t fly. Sorry that you wasted so much time in a game with a marked deck, wevets.
I’m late to the party, but a couple off-hand comments.
Man that map is a pain in the ass to decipher. The flags and lack of colored map territories makes it almost impossible to decipher. Boo!
Also, isn’t a “Juggernaut” specifically referring to a Russia-Turkey alliance?
Yes, you are right, I realized that last night (I tend to be semantically challenged). In the end it works out the same-two Eastern powers mopping up the board.