Where do you get the idea that 750 ISIS fighters escaped detention? Link? No way would the Kurds want that to happen, they've been getting slaughtered by those head choppers for years.
Also, what makes you think that Turkey isn't in working with Russia and Syria? Seems to me that Erdogan is playing a part prescribed.
RE: US Abandon Kurds to Turkey, Syria and Russia Make Deal with Kurds as Turkey Invades