Actually, technically what he's doing is turning a neutral power into a hostile power. And while I certainly think it's a *shrewd* move on your part to place him in a position to be stabbed, I highly doubt you're going to court a war with the Turks, who have made it exceptionally clear what they will do to those who aid their enemies.
No, what I expect to happen is for you to move as you seem to be doing, then immediately stab the Austrians, pointing out to the Turks that you're helping them against Austria, with the assumption that the Turks will turn on me (ie: the not-so-helpful guy who insists on pinning people down in agreements), leaving you with one or two more centers, and hopefully giving you time to weaken the English before the Turks finish me.
Of course, I could be totally off base. It's late, and I haven't had enough caffiene. But I don't think I am ;)