Sorry, can't agree with that opinion.

1. It's a given that Turkey has supported the groups fighting the Syrian government. (It's hard to describe support that claims lives and sovereign territory as "muted.")
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2. Turkey has its worst nightmare on its southern borders: a nascent Kurdistan. Which in time might lead to a quarter of Turkey thinking they'd like to sign up. 

3. Russia doesn't have a problem with the Kurds. The Syrian government isn't fighting the Kurds either. In all the world, the only enemies the Kurds have today are Turkey and Islamic State. (There's that combination again!)

4. The USA and its allies didn't seek to "stir things up." They provided the Syrian opposition with arms, personnel, financing, training and intelligence. On the semi-sly, they further permitted Islamic State to advance into Syria and take over its oilfields in the east. Those being Islamic State's main source of revenue.