How do we know that Zubaidah knew Turki's phone number? He gave it to some interrogators he thought were Saudis, thinking it would get him off the hook. "Call him, he'll tell you what to do."
I never said it meant nothing but it did not mean he was aware of Atta's job any more than confirmation of his meeting in Prague meant the Iraqi knew exactly what was coming done the pike. Al Queda compartmentalized its operations and secrecy was widespread through out the organization.
Sounds like a smart gamble by Zubaidah but proves nothing in itself.